Welcome!
PDX- Portland International Airport?
I would start by reading all of the reviews you can find on the -15 kit. I'm not familiar with it so I will not opine, but generally Tamiya kits are a big step above Revell. They cost a lot more, however you have to consider the time you will invest and the added stuff you want to buy. It usually is worth going the extra mile. And of course you can always build the Revell kit too. I'd also repeat the question about the kit in the Aircraft forum.
PE compatability is something you will have to look into. I find it a bigger issue on aircraft than any other type of model. Again, the Aircraft forum is the place to ask.
I don't think there's really such a thing as a beginner airbrush. Lousy airbrushes hamper your ability to learn to get competent with the tool.
A good Badger or Iwata can be found for less than $ 100 and will suit your needs forever, even if you later add to the collection. A cheapo airbrush will land you back here asking questions about leaks, etc. Follow up on the Painting and Airbrush forum.
Look also at the website set up by Don Wheeler. I don't remember the url but its easy to find as it has his name in the address.
General questions can always be posted in the General Modeling Discussion forum, but that doesn't always get the traffic that the experts will find, so it pays to be specific.
Posting pictures. That's a common question. Do a forum search in Tips and techniques or Technical assistance. But mods cover your ears here; this forums search function isn't good. Often I find what I'm looking for comes up as posted on FSM through a Giggle search. Scan the matches and you'll see this forums address near the top.
You'll need to upload your photos, usually jpg.s, to a photo host site and then follow whatever that host's protocol is to copy a link and paste it here. That little button above that looks like a slide image of a mountain is the place to open a window and paste the url of your image.
Bill