Hello
I am interested in your offer. Answering your questions:
1. Yes, I am native polish speaker
2. Yes, I've done some works as an editor and proofreader, however, it wasn't for a polish site. There were some revisions of academic articles and/or thesis.
3. I am not 100% freelancer, however, I may spend up to 4 hours daily online during the week and up to 8 hours during weekends.
Thank you!