That's why there's a search facility
1) Would be near-impossible for anyone here to say with any certainty how many of the dried mushrooms you're getting would be 2-3 grams - far too variable. Depends on how big the shrooms are, how dry they are and many other things I can't think of right now. A scale would be much better - is there maybe a set of kitchen scales available? Would be better than nothing?
2) Redosing works best if you do it early enough. If you leave it too long the extra mushies tend to just keep you on the same level for longer - bit wasteful. For best results take the whole dose as one. As long as you don't go for a huge dose then you should be fine
3) Can be taken two nights running, but the effects are markedly reduced. Best to leave at least a week or so between dosing but you can get away with less - just won't have quite the same magic maybe.
4) Weed can be a great addition to mushrooms but will also potentiate them quite a bit. Another one that's hard to say as it varies so much from person to person. I frequently smoke like a chimney on mushies other hate to mix the two.
MDMA also mixes nicely (a hippyflip, as they say) for many but wouldn't advise it for a first time as it massively potentiates and changes the effects of the shrooms. I'd leave that till you're more familar with the funki-fungi alone first.
Speed doesn't tend to mix well with mushrooms (or any other psyches in my experience) so I'd avoid that completely.
5) If properly stored, dried shrooms will store for a long time with little loss of potency. Certainly months and possibly even years if very well stored. Outside of a fridge/freezer they won't last so long - maybe a few months at best, but probably less. They won't go mouldy unless they get wet.
6) I put my wet mushrooms on a warm radiator to dry generally, but other folks prefer to use no heat at all. A fan blowing over them helps.
Maybe have a flick through this here thread for more detailed answerd and happy shrooming