For the Windows and Context Menu caps, you will need to either mod the rubber dome caps from the Unicomp PC/5250 terminal emulator board or have someone with printing capabilities do a custom print for you. Unicomp does not seem to be willing to do so without a super large order, so try FenTek.
Same deal goes with media keys. You can grab the media keys from the Space Saver M, which has them as a sublayer of the F keys, or again do custom printing. I think Unicomp would be able to do that, but once again it's going to cost you a lot of money.
I'm in the same boat as you because I'm trying to add Windows and media keys to my Terminal Model Fs, but so far it looks like it's going to be costly. However, if I can get more people on board, we could try and do a group buy for custom printed keys.