When can my hand fed baby parakeet start eating seeds?

I have a very young parakeet whom was badly mutilated by another parakeet. I managed to save him (though I am unsure how he survived). I have been feeding him formula for birds but he requires feedings every two hours. I am anxious for when he can eat on his own but i have no idea on how long that is going to take and I don’t want to push him until he is ready.
He is approximately 2 weeks old.

Can you hand train a parakeet if you let them out before hand training?

I’ve had my parakeet for a few days now and the second day I let her fly around the bathroom. I was able to catch her after I let her fly/perch in the bathroom. I read on the internet (I can’t quite remember the site right now) that you can’t let your parakeet fly around until you hand train them.

Can you use a liquid paint striper on a bird cage to remove the paint instead of sanding it by hand?

I understand I will need to get all the loose paint off and I will need to wash the cage good before I repaint it with the proper paint that is safe for birds.

PARAKEET HELP! What is the difference of a hand fed parakeet and a parakeet that is not hand fed?

Should I buy a parakeet from the pet store? Are the birds at the pet store mean? Do they bite all the time? Are they hand fed? Can they be trained if there from the pet store? Please help.