Yep, that's the most solid strategy right now if you can afford it.Bombs are ideal as they don't damage the hull. However, needing 30? I've never needed that many.
You actually CAN kill enemy crew without disabling the medbay first. One method is teleporting to the cockpit, and have a second boarding party teleported to the room immediately below it to hit the guy on his way to the medbay. Ideally, use rocks for the first and mantii for the second.
Another, devious one, is to simply hit the medbay with a bomb/missile just as he arrives to heal. With any luck you'll damage or even take it down and kill the injured crew in one fell swoop. Then it's a matter of having four guys on the destroyed medbay and praying (again, a combination of rocks and mantii, plus dominion over the technique of "switching fighting places" helps a lot).
Finally, if you simply can't manage to kil them all (and sometimes you can't), destroying the flagship the "normal" way isn't THAT hard, as long as you can get past Stage 2's defenses.
True, I think 30 is a safe bet though. Nothing worse than bombing the med bay and seeing 4 guys putting out the flames and then the ship cloaks before you can continue bombing it.
I've never been lucky enough to form two away teams on normal. That seems like a good strategy, assuming you can return both crews safely.