I have a few questions on better understanding mortgages in Switzerland for financing a property for staying:
If the downpayment is 35%, I can only take the first mortgage for the 65% of the property’s value. I only have to pay interest “for ever” and avoid amortization. Most mortgage calculators from bank portals don’t make the distinction very clear.

What does “for ever” mean? If I get a fixedrate mortgage does this interest apply for life? I see fixedrate interest rate mortgages mostly associated with the second mortgage.

If the first mortgage has a fixed interest rate for a given term (e.g., 10y), what happens after the 10years? Do I get then a fluctuating interest rate according to the market?

When can I refinance the first mortgage? If interest rates drop can I negotiate a new mortgage with the same or another bank before the fixed interest rate term (e.g., 10y). That wouldn’t make much sense.

If the value of the property increases, can I negotiate a new mortgage to get 65% of the increased value and keep the difference between the old mortgage value and the new one for investing in the market?

What’s the maximum amount that can go to downpayment from Pillar 2/3a? Is it half of the total downpayment of 35% or is this capped to half the downpayment, assuming a downpayment of 20%?