combat squads

Hi all, I think this is fairly clear cut but I want to check in case I am missing something before I use it in a game. The Grey Knight Grand Master's Grand Strategy rule allows him to buff D3 units with various rules before the game begins. My question is, can you buff a unit, then split it...

Quick clarification: Razorbacks can take 6 marines. Can I make a 10 man tact squad, separate it out into 2 combat squads (say 5 and 5) and give each Combat Squad a Razorback? Or since the original squad is 10 man strong, the Rhino is the only option for a dedicated transport? Thanks in advance.

If I split a Tactcal Squad into combat squads, can one of the squads start embarked in a Rhino.