2) Liara (my FemShep's lover )
3) Ashley (my MaleShep's lover, whom he cheated on with Miranda)
Ditto on both counts, though I can one up you on the latter. My MaleShep not only cheated on Ashley with Miranda (after a quickie with Jack) but promptly cheated on her too in favour of a certain Quarian girl...so yes, my MaleShep is a complete bastard and a dog.
My FemShep on the other hand was steadfastly loyal to Liara...though only because the game designers wouldn't let her get some Quarian action too.
That being said, I intend to do another play-through of both games with a new character at some point where everyone dies on the suicide mission except for the one or two team members I need for Shepard to survive. I also intend to do one where everyone survives in order to get that achievement.
My FemShep already managed to keep everyone alive, though I'm about halfway through a replay of my MaleShep in which I intend to arrange for him to end up with the one or two needed to survive, but more specifically, as a paragon that got Tali exiled, blew up all the Geth heretics and anything else I can think of to sabotage his chances of surviving the Reapers in ME3. He already killed the Rachni queen in ME1 so he's already off to a good start. At some point I'll have to go back and finish that game and get my LoserShep save ready!
As for Garrus, I honestly never used him much in ME1, my FemShep was a soldier so I pretty much stuck exclusively with Liara and Tali to keep a good balance of abilities. I did have a ME1 character save about a third done where the character was sticking exclusively with Garrus and Wrex to get some achievement or another. Again, I never got around to finishing it (though I backed up all my saves so I may yet someday) but I was surprised at how much more input those two had on conversations. Wrex in particular added an irreverence that I found really entertaining. I do have a little soft spot for Garrus though. His stock went up after turning out the be Archangel (did anyone NOT see that coming a parsec away?) but he has a kind of emo/angsty air that I find mildly tiresome.
Oh and Mordin is clearly the breakout character of ME2.