Firestone and Airlift do install kits, and they also sell parts separately.
You will need a pressure switch for the tank, so the compressor shuts off at a reasonable PSI (eg. firestone part number 9016)
You will need a pressure gauge to check the pressure in the bags (almost anything will work great, around 0-100psi)
Might be a good idea to also install a pressure gauge in the tank so you can monitor it.
I think what you're thinking in regards to solenoids is electric over air. very possible to use, but you'll need to have 1 that fills the bags and 1 that dumps the air. and if you want to run separate pressures to each bag, you'll need 4 in total, but it does prevent you from having to run airlines to the cab.
A much simpler solution would be instead to run with a paddle switch (airlift 21703, which fills in one direction and dumps in the other.) Again, if you want to run the bags at different pressures, you would need 2 of these. 1 airline run in from the tank as supply, and 2 running out (1 from each switch) for delivery to the bags.
Plastic airline and fittings are readily available at any truck shop - very commonly used for air brakes. highly recommended to go there instead of an automotive supply place for those.
It is difficult to find kits for install without the bags. Firestone does sell parts individually, although it may be hard to find some of them. Link to the install manual including part numbers:
https://www.firestoneip.com/rr-kit-install-manuals/W217602025.pdf