ᐅ Floor Plan Optimization for a Single-Family Home with Basement on a Small Plot

Hello everyone!
After reading here for quite some time (and checking out nearly all floor plan questions for similar lot sizes and building dimensions), we now have some questions about the preliminary design from our builder.
Our situation is similar to the forum post from Wednesday, but our main focus is on the basement J
This is the first draft based on a rough idea of what we envision and what is important to us (the design seems quickly done to me—see the projecting dormer—or is that common nowadays?), but overall all our requests have been considered. We see room for improvement especially in the basement level, the basement stairs/daylight wells, and the size of the living/dining area (probably only fixable with a larger house footprint). The upper floor works well for us.
Independently from the builder, we came up with a similar floor plan that meets our needs; it is nothing “special” but fits our ideas well.
We would appreciate it if some of you could share practical tips or suggestions for changes so that we can respond to the builder and discuss possible deviations.
Feel free to be thorough and please also point out any potentially major planning mistakes.
I have attached the following:

• Site plan assumed by the builder
• Builder’s planning (floor plans, section, exterior view)
• Our modified floor plans based on the builder’s draft (larger living/dining area, smaller kitchen, different basement stairs)

Development Plan / Restrictions

Lot size: approx. 360 m² (still not fully measured, as the plot is being subdivided)
Slope: no
Floor area ratio (FAR): 0.4
Floor space index (FSI): 0.8
Building envelope, building line and boundary: see site plan; 3 m (approx. 10 ft) on three sides, less on street side due to protected green strip with fruit trees (not our property); open building style
Edge development: no (usually allowed for townhouses, but specifically excluded for carports and garages in the development plan); edge development allowed for uncovered parking spaces
Number of parking spaces: 2
Number of stories allowed: 1-2 full stories
Roof type: gable roof (up to 38°), shed roof, flat roof (up to 25°)
Architectural style: classic-modern?
Orientation: ridge line along the street
Maximum heights / limits: eaves height max. 7.50 m (24.6 ft) above the access road (lot lies slightly below street level)
Additional requirements: none

Homeowner Requirements

Style, roof shape, building type: classic/modern detached single-family house, gable roof 38°, knee wall preferably raised to 1 m (3 ft)
Basement, number of floors: basement included, 1.5 floors
Number of people, ages: 2 (both 29), 1 child (1.5 years), at least 1 more (preferably 2) planned
Room requirements on ground floor (GF), upper floor (UF)
GF: kitchen (with sliding door, can be smaller, no separate dining area), living/dining area (currently about 32 m² (344 sq ft), our furniture is designed for this and we would like to keep it), future master bedroom, bathroom with shower (house should theoretically be usable on one level in an age-appropriate way)
UF: 3 children’s rooms, bathroom
Basement: utility room, technical room, workshop, office/guest room
Office (family use or home office?): office desired (in basement), home office at least once a week
Guests per year: about twice a month 2 people, every two weeks 1 person → guest room desired (can later be combined with office in the basement if a bedroom is needed on the ground floor)
Open or closed architecture: closed
Conservative or modern construction: rather conservative
Open kitchen, cooking island: no, smaller cooking area, separated by sliding door
Number of dining seats: permanently for 5 (current dining table has 8 seats)
Fireplace: yes, preferred
Music / stereo wall: no
Balcony, roof terrace: no
Garage, carport: no
Vegetable garden, greenhouse: some vegetable garden, so we want to place the building close to the build boundary to maximize garden space

Additional wishes / special features / daily routine, also reasons why some things should or should not be: none

House Design
Planner: planner from a building company; the second attached version is our own adjusted “solution” with the house widened by 0.5 m (approx. 1.6 ft) and furniture drawn in the living/dining and bedroom areas which we already own.
What do you especially like?: the solution with a coat area and shower niche on the ground floor, the stairs, level, masonry showers, spacious children’s rooms, fireplace location between living and dining areas, large home office/guest room in basement, where both “uses” can be nicely combined.
Why?: we had not thought of the coat and shower concept in the floor plan ideas, find it practical and reasonably age-appropriate (though the dimensions could be slightly wider), and had no clue where best to put a fireplace.
What don’t you like? Why?: living/dining area too small, at 22 m² (237 sq ft) we cannot fit our furniture, kitchen is too large, we don’t need a separate seating area in the kitchen (we currently eat all meals in the dining area), the exterior basement stairs with the bend take up too much space, and we don’t want a carport as it would have to be inside the building zone (uncovered parking is allowed as edge development), the concrete daylight wells in the basement.

• Regarding the basement daylight wells: my father (landscape architect) suggests a landscaped slope on that side of the house instead of concrete daylight wells (I roughly marked some slope lines on our design) with stairs integrated into the slope at the rear of the house. What do you think of this option? We are unsure about stair drainage for rain, but this should be manageable with proper drainage (could be routed by pipe to the cistern we must install per development plan). Any other ideas?

Price estimate from architect/planner: not yet available, initial rough offer before planning (130 m² (1400 sq ft) with basement) was 315,000 including standard ancillary construction costs, but with a “standard basement”; we might need a waterproof concrete shell (“white tub”), estimated extra cost about 20,000 according to the builder
Personal price limit for the house: 340,000 (furniture is already owned from current large apartment (126 m² (1356 sq ft) living space), kitchen belongs to us and only needs minor changes, cost covered separately)
Preferred heating technology: we considered a ground source heat pump, but the builder has had problems twice in the building area with insufficient supply temperature and therefore recommends an air-to-water heat pump on the south side of the house. Has anyone had experience with this?

If you have to give up something, what details/features?
Can give up: dormer, large kitchen, fully heated basement
Cannot give up: basement (due to small lot and 3 children planned), bedroom on ground floor, bathroom with shower on ground floor

Why is the layout the way it is now?
Draft from planner after a brief initial discussion about our preferences (we did not provide a detailed list of requirements)
Which wishes were implemented by the architect? bedroom on ground floor, bathroom with shower, staircase design, bathroom with shower and tub on upper floor, basement with office
What do you think works well or poorly? we like the overall distribution of floors, but are not yet convinced by the basement layout.

What is the most important/basic question about the floor plan in 130 characters?
Any ideas to improve the basement (e.g., no bent stairs, maybe no basement hallway at stairs, maybe no daylight wells)? Any improvements for other floors (e.g., larger living/dining area)? Is there any place to add a laundry chute (nice to have but not essential)?

We look forward to your ideas and feedback J

Best regards and many thanks in advance!