1
1. i just mined a tiny bit of bitbar however it says immature, and is taking forever to mature. Is it okay to turn off my pc or will this cause me to lose my 0.18 or whatever bit bar?
it takes 520 confirms for coins to mature. No u do not need to have the wallet online for this, its the blocks that are generated on blockchain that give confirmations, so once u have 6 confirms the block will most likely not be orphaned and u can safely switch off ur comp
2. with all wallets, do you need to have them closed when you copy the wallet.dat
no u do not need to, u can just copy and past across the file somewhere else... though for safety reasons it can be wise to always lock the wallet b4 backing it up by "Encrypt wallet" option... as anyone else if they got hold of ur wallet.dat could send the coins to another addy
so as u describing in 3.. that is the correct way and safely locked the wallet, others can view your balance and activity as its broardcast on the blockchain, but as they don't have the password they can not send coins from wallet... and they can not even create a new address for the wallet to receive coins.. good way of testing
and AFAIK it IS possible to mine on a locked wallet, though proof of stake won't work... well it like that for PPCoin
hope this helps