1. As mentioned in the FAQ, you may have it compatible with whichever platforms you want, as long as Windows AND/OR mobile is included. "Any" includes play in browser.
2. Unfortunately, yes. This is so I can make sure their profile does not break the Jam rules. I understand that I know you both irl, but I will not give out exceptions under any circumstances.
3. No.
4. You can give compliments, but unless the creator(s) gave their consent to criticism, you may not give criticism, constructive or otherwise.
I hope this answers your questions.