imo

1) mas maliit ang M2 than the micro SD. SE K800i and 610i uses M2. Earlier models dito like the 600 and the 750 uses the micro SD.

2) not necessarily.... but most phones developed still don't have the capability to handle more than 1GB kasi these memory modules (> 1GB) have not yet been developed prior to their release. theoretically, a software upgrade on the fone should make it possible to handle more than 1GB memories.

hth