To tell the truth I cannot advise you to study Computer Science in Poland. Although its a well-known college it will not give you anything in English. If you want to move to USA it could be better study your BA in Turkey.
As far as I remember who does not hold permit to settle is not allowed buy a house.I do not know about buying a land and build a house how it works.
- If you aren't a farmer, you won't be allowed to buy land.
If you would like to be a farmer you have to graduate from agriculture university so that means also he is not allowed to get any grants or social benefits.