I recently got a 6 oz. popcorn machine for my wife, I've learned a lot in the last month or two about this.
I hear that MegaPop (sometimes called Pop Weaver) is the kind of kernels that you'd like to get.
You probably want to use Flavacol salt, they have a standard and premier option.  You can get a quart for about $2.50.
Oil can be tricky.  Peanut oil was really good for us and caramel popcorn.  I think overall for the price I'd use canola oil.  There's a reason taht everyone wants to use coconut oil -- I think it's best overall.  However apparently it's really bad for you to use partially hydrogenated oil, you know if you care.  =)  Problem is, pure coconut oil that I've found from health food stores runs about $9.00 for 13-15 batches of popcorn.  Not exactly cheap.  Anyhow, I'm rambling.
Check out 
www.ht-express.com, that's the site I've found to be the most friendly and informative for my needs.  I'm still looking for a local distributor for this kind of thing, shipping can be expensive.
Good luck.  =)