i have 4 macros set up on my PiP keys when I swap them in and out. each macro selects whichever toon is going to be my main focus screen and sets them both to focus and party leader if possible. each macro looks like this:

Account 1 (these are the same on each account, but with different names
/focus Kauldwynn
/focus Bynton
/focus Lansylot
(these are repeated for each toon name in that realm list)
(then after all the /focus commands)
/jamba-invite team
/promote
(then the /jamba autofollow command. can't remember right off hand what the right one is for that now.)

everytime I hit the PiP keys for Keyclone to swap out, it changes both party leader and focus to that toon. they all have the commands by name, so no messup on who gets set to focus.

I also have three other separate macros set to different keys. they are:

Clear Target
/cleartarget

Clear Focus
/clearfocus

Target Focus
/focus target
(this I have so incase I need to set someone else as my focus while in BGs or Instances if I'm not the tank or primary healer.)

As for the mounting, use Ugh's suggestion, it works. Make sure you reset your /follow focus once everyone's in their vehicles tho, plus the /follow focus does not work, or atleast for me, if you're in control or posession of anything. found this out while in the Death Knight starting zone. Couldn't even get it to follow my main eye/orb cause my physical bodies were back at Ebonhold. If anyone knows a work around for this please feel free to post it. However the /follow did not work here, my team still did get quest credit when I preformed actions.