I would suggest that if you put them all in a jar on the desk over a fairly short time you will find which will become your favourites and which ones you will dispose off. Not a definitve answer but I bought a "Hobby Pack" of ten brushes mainly for the finer brushes but have found a use for all of them at different times.
In regards to weathering though, my thoughts are that the surface you are weathering would been dulled off over time, the only surfaces that would be still gloss would be in the case of a new vehicle that has got dirty, (mud, dust and the like). I havent progressed to using powders and the like, just using what is at hand basically to ry and re-create what I think things would like. At the moment I am trying to make a 1940 Ford pickup (hotrod version) look like an old farm work vehicle.
I use a cotton bud (Q-tip) to wet the rear of the decal sheet where the decal is and a little water on the front then pick them off with tweezers if small or slide them off directly onto the model if larger. That way I dont have to cut up the sheet at all and they dont curl up.
I have just had to strip a body for the first time and have found that Dot 3 brake fluid and a medium toothbrush was the easiest for me. A tip as well for you. I couldnt find a container that would fit the body horizontally as I have seen so many times here and ended up with a container that is for storing flour/sugar/rice. It is tall 12" or 300mm and 4" or 100mm square. An unexpected bonus was that the entire body is immersed save for the very front or back depending on which way you put the body in, as it will float, but attach a plastic peg and when the lid goes on, it pushes it down into the brake fluid. Also because it is designed to keep food fresh it is airtight (No odours) and watertight (no Spills). Around 36 hours and everything came off and back to bare shell with no damage to the shell. I found it easy enough to find something else to do in that timeframe. Hope this helps.
Another idea for your driveway is to use gyprock and remove the paper from one side, basically gives you plaster board that can be painted, dyed and stained to suit. Very easy to simulate cracks etc. in it too. I think its called dry wall in the US and there are some fine videos on Youtube for its uses. Youtube is also a great spot to get ideas from as well as from this forum.
Envious 8420. The twist ties you spoke about on the spool should be available from any gardening shop. Its used to stake plants up. Well it is here in Aus anyway and pretty sure I have seen it in clear although a lot is green in colour.
Curtain sidedtrailers are easier and quicker to load as you can open them up all the way and just load pallet after pallet. If the sides are solid you can only load from the rear and use a pallet lifter.