It is described in detail in the KfW FAQ that as soon as there is a necessary connection with the funding object, the planning services can be billed through the energy consultant, even a structural engineer.
Don’t think you’ll find a bank that does KfW for me
Yes, it is possible, you just have to ask around a bit. And yes, with the 18k repayment subsidy and the minimum term of only 4 years, the loan is even worth it if you have to pay an energy consultant at 50% and even if you don’t actually need a loan.
And yes, with the 18k repayment grant and the minimum term of only 4 years, the loan is even worthwhile if you still have to pay 50% for an energy consultant and if you actually don't need a loan at all.
Yes, that's how I see it too, but I'm just not quite sure how to proceed... I would definitely set aside the "surplus" money and pay off as much as possible immediately.