Does computer receive bonuses ....

[cordash]

if I start with 2 civs on a team? Do they target my team more aggresively then each other simply because I have a team?

 

[jimbob27]

No, as far as I know they don't get any bonuses.

Its likely the opposite is true. They'll be less likely to target you because they'll see the combined strength of the team, and pick on a weaker target.