Hi Laggy,
Q1:
no idea for sqs goto's, sqf code with Param1/2 seems to work *pretty* well though !
Maybe BIS drops sqs support slowly ?
Q2a:
Didnt have any references but I cant imagine that savegames are bound to players ID's
Q2b:
There are definitely issues with save games in Arma2, still. These issues are legendary to my experience and go back down to all OFP releases (didnt get involved with Arma1 much).
Particularely spawned markers (createmarker...) are practically undefined after a reload for example.
Won't even know whats all missing in these 5-30 MB data bunches
On the other hand the transfer of mission relevant "native" data between campaign missions (WeaponPool, SaveVariables,..) always seemed to be raltivley solid compared to somewhat complex mission specifics.