Law / Polish resident card questions (got accepted at Jagiellonian University) [5]

Hey there, I am living in Turkey and I got acceptance from Jagiellonian University. Like in 1 month I will go to Poland for enrollment. Instead of Visa, I would like to apply for Polish resident card and there are two things I am really confused about.

First of all, I see, I need an insurance. Can I buy or should I buy it in Poland?
Secondly, for getting this card I need to prove monthly income+ money in bank? What if except tuition fee I do not have big amount of money in bank but I have income monthly 2.000zl? (from different country). or when I go to Poland if I open a bank account and put my tuition fee in bank and "show them like I have money" does it work?

Law / UK connected flights and Karta Pobytu (non-EU country) [7]

Hello everyone! I am currently a student in Poland. I am from a non-EU country. I do not have any visa or something else other than Karta Pobytu. I want to book a ticket to Spain but the flight is UK connected. Can I just go to UK with using Karta Pobytu even if I am not a Polish citizen? I will show them my 2nd ticket which proves that in next 24 hours I have a flight to Spain.

I am looking forward to get an answer from the people who have experienced this situation before. Thanks in advance.

Regards.