alright, my thoughts on the cover:
Cap is Cap. Period.
The two robots I'm gonna take a stab and say they're Vision 2 and Ultron. Now, Fury already rejected Hank's attempt at putting the androids on the Ultimates in issue #6, but what if Tony stepped in and combined the two robots with his Iron-tech armor. He could pass them off as his invention (with Hank's blessing since he already knows his name is bad publicity incarnate) and therefore there'd be no public backlash to their joining the team.
The four guys on the ground behing Cap and the robots I have no idea.
Captain Britain is there, not sure which Captain the other one is.
And the giant guy is obviously Goliath.
As for when this is supposed to take place in relation to the rest of Ultimates 2, I'm assuming this takes place during the six-week gap in #7 (or to make it easier, between 6 and 7). This is due to Black Widow having her suit, and Hawkeye still being alive in the issue.