Your posts are confusing because they are contradicting.
K.I.S.S.
1) Just use heli-coils. They will be plenty strong enough for what your doing. Timeserts are better, but unnecessary for this job.
2) Go ahead and do the other stock bolt hole if you wish, but do not try and re-heli-coil a heli-coiled-hole.
3) Yes, use a LITTLE Red loctite on the outside of the heli-coil to secure the heli-coil in the hole, don't get it inside the help-coil, the and let it dry overnight. Don't loctite the bolt that goes into that hole or the whole mess will back out when you pull the bolt later.
4) Yes, tape off the drill bit. The heli-coil kit should have the correct drill bit in it. Don't drill too far.
5) DEALER?!? You'd take it to the DEALER for a heli-coil?? You'd pay them $100 and wait a week
Up to you. Like I said. If you aren't comfortable doing this job yourself, take a 12-pack to your local auto or motorcycle shop, they might even have timeserts there.