Flanker. You want the stronger flanker at blindside and the quicker one at openside. I would guess openside for you so number 7
Flank, maybe number 8. Depends on what your team needs, but definitely in the back row
If your tall ither second row so number 4 or 5 and number 8
Wherever the coach wants you to play.
Lock as a lock you will have to compete for the ball in the line outs and push in the scrums as a forward your strength will be very useful but in the loose you should try and run good support lines look at Toby Faletau's try for Wales vs Tonga chasing behind the backs will wear you out quickly.
Well, if you're one of the tallest of all your team mates, I think you could be a lock. Since you said you're very strong, that means you have the legs for the scrummaging. Being a forward, you don't have to be so concerned about your kicking skill. And trust me, forwards are in the middle of the action.