I play medium to high live MTTs mostly locally whenever they come around and one thing Im always questioning during play is whether I should 3 bet with AQ, AJ, and even sometimes AK and suited A10 preflop when in position or in the blinds? This is usually during early to middle stages of a tournament when everyone is still pretty deep when I ask myself this.   

Should I be 3 betting with these hands preflop more frequently in order to gain information?

What position should I be in if I should do this at all? Late position or in the blinds?

I know they say to control the pot size in early stages of tournaments, does that apply here?