ᐅ Floor plan house design (access via slope)

Hello,
we have now purchased a 505 sqm (approximately 5,435 sq ft) plot of land.
It is located on a slope about 2.50 m (8 feet) high, followed by an almost flat area (2 m (6.5 feet) elevation over the 25 m (82 feet) length of the plot).
See the rough location sketch we created: 3D-Lage_nur-grob.jpg
The width of the plot is 20 m (66 feet), and the currently planned house width of 8.5 m (28 feet) is already the maximum possible.

Development Plan / Restrictions:
Plot size: 500 sqm (20 x 25 m) (21500 sq ft; 66 x 82 feet)
Slope: embankment at the entrance area, then almost level.
Adjacent buildings: none
Number of parking spaces: 2 (a standard garage and a carport (length = 650 cm (21 feet 4 inches)) planned side by side)
Number of floors: (utility) basement, ground floor, and upper floor (knee wall 120 cm (4 feet))
Roof type: gable roof with 35° pitch

Homeowners' Requirements
Number of people, age: 2, nearly 60 years old
Room requirements on ground and upper floors:
On the ground floor: guest room, living room, kitchen (kitchen and living room separated by sliding door!), guest bathroom with shower.
Upper floor: 2 (or 3) bedrooms plus bathroom.
Office: family use or home office? Partly planned on the upper floor by the gallery (or in the guest room on the ground floor)
Conservative or modern design: rather conservative
Open kitchen, kitchen island: no open kitchen; kitchen island yes!
Number of dining seats: 6 (up to 10 for gatherings)
Fireplace: no
Music/sound wall: rather no, nothing big
Balcony, roof terrace: only a terrace on the garage beside the dining area planned
Garage, carport: yes, yes
Utility garden, greenhouse: no

Note:
- The front door must be approximately where it currently is due to crossing the 2.50 m (8 feet) high embankment.
- The basement has a ground-level entrance door (laundry room, workshop).
- The house width is limited to 8.50 m (28 feet).

House Design
Planned by:
- Architect: Yes, basic concept from us

What do you particularly like?
Everything on the ground floor is planned on 65 sqm (700 sq ft) (bathroom, kitchen, stairwell, living room, dining area).
Hallway with built-in closet in a niche; also, refrigerator and oven are recessed in a niche.

What do you not like?
Are there enough "walls" for wardrobes?
Is the dining area big enough for up to 10 people (with an extendable table)?

Cost Estimate according to Architect/Planner:
...
Preferred heating technology:
Geothermal heat

If you have to give up something, which details/extensions could you do without:
- The bedroom on the ground floor could be a bit smaller (down to 12 sqm (130 sq ft))
- The bedroom on the upper floor could be smaller (currently 18.7 sqm (201 sq ft))
What you cannot give up:
- Living room and dining area must be separated by a sliding door!
- Guest room on the ground floor (also as a fallback if one has difficulty with stairs!),
- Kitchen island,

Why has the design turned out as it is now?
- Our wishes were implemented, e.g., niches for coat storage in the hallway and kitchen (for refrigerator and tall oven).
- Two walls in the upper floor with a 45° angle to make it a bit more open.
- Open gallery on the upper floor (which could still be closed with drywall).
- Space for two bicycles near the basement door.
- Carport easily accessible even for a camper (650 cm (21 feet 4 inches) long).

What is the most important/main question about the floor plan in 130 characters?
Are the rooms (living, dining, kitchen) large enough or too tight? Only for 2 people. Is the bathroom with 90 cm (35 inches) shower sufficient? Also for possible future care needs?

Is there a north arrow included, or did I miss it?

Why are you choosing such an elaborate staircase to the ground floor instead of opting for a grand, level entrance area at the "basement level"? A nicely spacious glazed entrance with a cloakroom and all the extras. You will have to go up anyway, but it would be easier and more attractive inside the house, and you would have more space on the ground floor for the terrace and garden.

Access through the basement was also considered, but since it is a utility basement (without insulation), this would involve additional costs in the five-digit range.
Also, access via, for example, 5 steps, 1m (3 feet 3 inches) level, 5 steps, 1m (3 feet 3 inches) level, 5 steps, ... is less strenuous.
And you wouldn’t really gain much space in the ground floor hallway either (OK, the built-in closet measuring 120cm x 50cm (47 inches x 20 inches) would be eliminated).
But a main entrance in the basement is not an option.
And the "complex" access to the ground floor, which is anyway "lost" space, does not reduce any usable garden or terrace areas (in the southwest).

North arrows, sorry, you’re right:
North is roughly "bottom left" in the images, see here two images with north arrow

Since you’re asking if 10 people can fit in the dining room: that will be quite tight with only 37sqm (400 sq ft) for dining, cooking, and living. This is because you are insisting on fitting a bedroom into the small floor plan. Considering the age and the understandable desire to have everything on one level, wouldn’t it be better to build a bungalow on the basement instead?

Due to the slope, a basement is necessary or at least cost-effective; otherwise, yes: it would have been built without a basement.

I wouldn’t want to deal with that “walk” from the (too small) garage to the front door going around the outside! Surely groceries will have to be carried through the utility room or basement using some kind of system.

The space for “dining” is a bad joke. It looks like a 49 m² (528 sq ft) apartment to me. And if an architect placed that closet in the bedroom right in front of the bed, I would seriously reconsider.

I would never build (or have built) it like that for the amount of money involved! A proper, better solution is definitely needed.