Is financing feasible this way?

Hello everyone,
my wife and I have been following along here for a while and now also want to have our project checked for defects or generally have the feasibility assessed.
General information about us:
33/26 years old
1 child planned (in 4-5 years)
both permanently employed full-time

Income situation:
Net income him 2200€ (from August next year 2400€)
Net income her 1600€
Plus 3000€ holiday/Christmas bonus
Equity: 64000€ land, in cash we would like to contribute 60000€

Expenses:
Cold rent 450€
Warm rent 700€
Electricity 90€
Telecommunication 100€

Mobility costs:
1.5 cars: fuel, insurance, service, tax 600€

Insurances:
Currently around 150€

Living expenses:
approx. 500€

Savings:
1000€ (daily allowance, building savings contract, savings book)
500€ vacations

Income and expenditure totals:
Results in a balance of 160€
Sum of cold rent and dispensable savings:
450€ (cold rent) + 300€ (from vacation) + 500€ (savings rate) = 1250€

[B]General information about the property: [/B]
Plot: 680m²; 22.5m x 30m
Standard land value is not meaningful, as the last data were collected from the municipality in 2008
The whole thing is to be a new build in timber frame construction (Hanse Haus) on a slab foundation with approx. 150m²


Construction or purchase costs:
Costs for earthworks/outdoor facilities (slope location) 75000€
Costs for the house 240000€; turnkey without painter/floor layer work, doors
Sum for the remaining interior work 22000€
Additional construction/acquisition costs 12500€

Other costs:
10000€ for interior furnishings

Cost summary:
Total costs 359500€
Equity 60000€
Financing amount 300000€

We have an offer for an annuity loan with 1.81% interest, 20 years fixed interest rate, a monthly payment of 1200€, prepayments of 5% p.a., 4 possible repayment rate changes. We can prepay at least 2000€ annually. This would leave a remaining debt of 37000€ after 20 years.

Is this all feasible for us? If yes, are there any suggestions for improvement?

One of the few apparently healthy financings. What positions are included in the 75k€ and 12.5k€? Depending on the standard, the 240k€ for the house is too little. What about the kitchen and so on? Where is the buffer? Where is the staging? Why without doors? What does [Hanglage] mean? Why no basement on a slope?

Is easy to present. But check construction and ancillary costs. Seems to be set too low. I would estimate that 100,000 are missing.

One of the few apparently healthy financings. What positions are included in the 75k€ and 12.5k€? Depending on the standard, 240k€ for the house is too little. What about the kitchen and co.? Where is the buffer? Where is the upgrade? Why without doors? What does hillside location mean? Why no basement on a hill?

Let's start from the beginning: 75k€ includes earthworks/slope stabilization for 60k€, the rest is flat-rate for terrace, paving, and garden.
12.5k€ includes 1000€ for the entry of the land charge, 3000€ for surveying, 1000€ building permit, 4350€ connection fees, 600€ for insurances, the rest as reserve.
We arrive at the 240k€ because we will take a catalogue house from Hanse Haus and receive an additional 5% discount. Since we also live not far from the company headquarters, we have already completed a preliminary selection and have (hopefully) included most of the upgrades in the purchase price. I have still planned another 3000€ into the house price here.
The doors are omitted because we save some money by installing them ourselves (carpenter in the family) and we are thus not under time pressure regarding the spackling of the walls.
The costs for the kitchen are mostly covered by an existing voucher, the rest (2000€) is integrated into the item interior furnishings.
As a buffer, we have 3 net monthly salaries plus the Bavarian home ownership grant. Together about 20000€.
Hillside location in our case means that the property rises away from the street (5.5m over the 30m property length). The immediate neighboring plot was built on two weeks ago; there, the earthworks, which were more extensive than ours will be, amounted to a lower amount.
We forgo a basement due to the resulting additional costs of around 50000€.

Well, does the prefab house really fit this sloping plot perfectly? I have serious doubts. Given the incline, I can’t imagine how to build a house without a basement there; could you sketch that out for us? Overall, I see the financing as being in the green, but I need a bit more guidance on a prefab house without a basement on a sloping plot.

The plot rises by 2 meters over the first 5 meters. After 4 meters, the building envelope begins. Our plan is now to make a cut at 2-2.5 meters height up to 4 meters before the end of the plot and then slope the remaining hillside at a 45° angle and secure it. This has already been implemented in many houses here. As a result, we "lose" about 10 meters in plot length and thus still have about 10m x 16m of green space/garden behind the house.

Well, whether the offer house fits this hillside plot so perfectly? I have very serious doubts

The almost identical house (in exterior dimensions) was erected on the mentioned neighboring plot 2 weeks ago