Bleh too long of a paragraph... to answer your first question, moving filter media should be just fine. I assume you'll be moving all your substrate and plants over from your 2.5g to the mini-m so it really should be all ready set and go to move species in right away. Just move the water as well =)
As for the plants, dwarf hairgrass will root itself and not be easy to take out to remove/move but depending how far you're moving it, you might need to break down the entire tank when you do move. Lower the water to the minimum almost touching the substrate, try to get all the fauna out, then move the tank on to something you can carry it on like a piece of wood shelfing. Put plastic wrap over the tank top and move it in your car... the substrate may move a bit the carpeted plant should be in tact.