Law / Temporary residence card to obtain a mortgage in Poland? [17]

Grzegorz has right.
I tried to apply for a loan for my boss who is Englishman (he is running a business in Poland) three months ago, and that was impossible.

Law / CHF loans & mortgages, customers in Poland left biting the bullet. Walking away? [20]

I used to work for a Polish bank and as far as I am aware it is almost impossible to force you to redeem.
In any case it is complicated and long lasting process, and I didn't hear any bank has executed the debt.

Real Estate / New Landlord - taxation on rental income [6]

You can pay tax in amount of 8.5% of rental income, to the limit of 4.000 EUR. On income above that you will pay 20% tax.
In any case you have to register in tax office before end of January for the following year.