Don't give up. You are away from your comfort zone but on your way to a great journey. 

Actually I never use primer for the interior but anyway.  TRM and andrei383 gave good advice for using spray cans and as PharmPony mentions try to go for a Tamiya fine primer. Now, some spray cans loose a little bit of pressure constantly and if that is your case you won't get an even finish not matter how good is your technique. Unfortunately that happened to me. So, when you buy spray cans avoid old looking ones.

Regarding brushes I have to confess that even though I own a hobby shop I go to a local small arts shop for advice. You want brushes that can take different types of thinner/paints.

And yes, Tamiya is hard to brush paint but try mixing two drops of tamiya paint with one drop of purified water. Water won't dry as fast as thinner and will give you a little more time to work.  Add water or paint as you see fit.

Old Revell or Airfix kits are inexpensive but can be very challenging for an inexperienced person. Trying to align the parts properly and filling gaps can be troublesome. Also you choose a big kit. Consider some of the "Easy Assembly" kits from Hobbyboss. The 1/72 are $10 MSRP and the 1/48 $23 MSRP.

I don't think removing the paint is a good idea at this point. You can easily get frustrated if you go back and don't see any progress.