Residence Permit for an American in Poland? Partner of a legal resident 90/180 day Schengen immigration policy

Hello! I have a couple of questions and would like to seek the advice of any of you living as expats (especially Americans) in Poland. I apologize if this is not the best venue for such questions and would also greatly appreciate any advice regarding another/better place to seek answers. Or maybe I should post it under "Law"?

I'm a US citizen currently living in Russia and considering spending a few months or years in Poland, possibly together with my girlfriend who has Polish residence. I make my living online and don't plan on looking for a job locally in Poland.

My questions:

1) Is it feasible/possible for Americans to get a residence permit under such conditions? (No work in Poland, but I can show sufficient income)

2) Is it possible to register as a partner (not actually married) of a legal resident of Poland. Does this make the process easier?

3) Does anyone know anything about a supposed bilateral agreement between the US and Poland which supersedes the usual 90/180 day Schengen immigration policy, allowing US citizens to stay in Poland longer (provided they exit the country at least briefly every 90 days)? I am very skeptical of any such policy because, even if this were so, it would mean that I couldn't (legally) set foot in any other Schengen state after my first 90 days in Poland. But still, I would be interested in any information or experience that people have with this policy.

Bardzo Dziekuje!

Hello,
Answering the first two questions, so it is possible. On the third question is also the answer.
We provide foreigners with an effective assistance and support in legalizing their stay and in a smooth integration in Poland. We are based in Krakow. Here our website: expatsinpoland.pl/ If you d'like to use our services, please contact us.

best regards

@Michael1922
Hope it is not too late to answer your questions.
1) Is it feasible/possible for Americans ...
A: Yes it is totally possible for American citizens to get a residence permit, but you have to get a temporary one first. You can make it a self-employed situation with sufficient income to obtain the permit.

2) Is it possible to register as a partner ...
A: Being a partner of a Polish resident in Poland doesn't make the process easier, unless you are the spouse of the Polish citizen. This has been my experience and it is the answer I got from legal service. I am not 100% sure of it though.

3) Does anyone know anything about ...
A: The bilateral agreement between Poland and US is supposed to allow American citizens to stay in Poland for 90 days and get out of Poland. For how many days to stay out of Poland before coming back, no one knows and nowhere says anything. In theory, you can stay in Poland for 90 days, and on the 90th day, you leave Poland and head to neighboring non-EU countries like Ukraine for 1 day, you can re-enter Poland without a problem, another 90 days should be granted. However, with border situation changes in recent 2 or 3 years, this deal doesnt work any more. And please do NOT cross into any Schengen countries when your 90 days is up, otherwise you may be facing huge fines and a black mark on your passport.