I laid on my stomach until I was 35 weeks with my son, it got too uncomfortable after that. Lol

I was told it was perfectly safe, and wont harm the baby to lay on your stomach as long as your comfortable.

Perfectly fine as long as you feel comfortable. The concerning position is laying flat on your back but not until around 16-20 ish weeks

Yes

No they always say lay on ur left side

As long as you are comfortable its fine. After a certain point it will be painful. At 3 weeks it doesn't matter honestly.

I did & never had any problem. I can’t sleep on my back or side. It’s not comfortable for me.

Maybe while it’s still small. I Don’t Think you can when you get bigger. I know you can with pillows that have a hole in it.