Mass-effect – What squad upgrades transfer with a Mass Effect 2 save-file import

There appears to be no benefit. While your character's level and skill selection transfers over, I don't seem to have retained any of my equipment or upgrades.

Normandy upgrades are retained, but those have other impacts across transferred saves as well (Suicide mission survival), so it's unlikely that you won't bring those over unless you actively avoided them.

Every Mass Effect 2 save file has a "QuestCompletion" variable that can be one of three values. Gibbed's save editor has dubbed these, "Quest Incomplete", "Lived To Fight Again", and "Went Out in a Blaze of Glory".

There is no "mission complete" save generated by ME2 like there is in ME1. Instead, every save file has this variable in one of the three states. Presumably, only saves where Shepard "Lived to Fight Again" will be viable to import, as Bioware has previously stated dead Commander Shephards won't be importable into ME3. (And obviously, you can't import without beating the game).

(Related: https://gaming.stackexchange.com/a/52493/336)

When importing into Mass Effect 3, you get to pick the actual save to import (i.e., quick, auto, or manual). Your save is always current, so there should be no worry about keeping your save "updated", other than simply saving normally from playing the game.