An external antenna isn't needed nearly as much on an airborne 2.4GHz as it was on the older 72MHz receivers. Same thing can apply to the transmitter antenna, many don't even have an external antenna any more. In fact, out of the entire length of a 2.4GHz receiver antenna, only the stripped end is actually accepting the signal. The rest of the antenna is actually a shielded coax cable, just like what is used on cable TV installations except smaller.
As far as the sanding tools go, you could also stop by an auto body repair supply shop and see what they carry. I found at a local one in my area sanding sponges that are great for sanding curved surfaces. They also are a great source of light weight fillers and solvents, even better than box stores like Lowes, Home Depot or Menards, not to mention less expensive since you can buy once and have for years or, at least until you hit the shelf life limit