Steve can give you some excellent advice about hi-power.
Now the way your gun is set up currently, you can compete in 3 gun quite well.
3 gun matches are IPSC or IDPA style matches. Only there will be stages for pistol, rifle, and shotgun.
The maximum range for rifle targets in these matches are entirely dependant upon what the limitations of the local range facilities are. At our local club matches we run rifle targets out to about 200 yards tops. Some clubs run out to 300 if their ranges allow it. There are a couple that run out to 500 +. (WC3gun last year, though this year we only went out to 300).
3 gun is a fast paced and very fun game.
Either way I would suggest that you search your local venues and see what kind of matches are available to you.
As for flaming, we don't really tolerate that kind of thing on TFL to much.