'Best' is a very subjective thing. If I were to make a personal recommendation, I'd go with the Ruger 10/22.
The one you can afford.
No.
Leave this to a gunsmith
Yes
50-200 USD
50-150 or so
50-500 USd
50-175 usd
50-100 USD
10-400 USD or so
Range 100-400 USD
25-150 USD depending on specifics