Sorry to regurgitate any past info, but some help would be great...I know zero about the AR platform.

1)I'm a lefty, is it imperative to purchase a Lefty AR or is it easily shot either way ?
2)I see there are many calibers available, for a starter is the 223 or 5.45 the sensible decision ?
3)Are most of you buying factory ammo to shoot(100 rounds a week), or reloading your requirement ?
4)What brand/model should I look at for a $1000-$1200 budget(not including scope) ?
5)And lastly: What options on the gun are needed/suggested by the members(charging handle, compensator, buttstock, etc) ?, I don't know what these terms refer to.

Thanks