1. Most card bonuses are only available for 1st time card holders... I'm not aware of any cards that can be churned anymore.

2. I'm not certain, but IMO, it's not much

3. I wouldn't apply for 5-6 cards in say a week.. especially not with the same bank - there are no fears of ineligibility, but there are real fears of not being approved at all.. I typically limit myself to a max of 2 cards per bank within a few months of each other..

But no, you wont be ineligible for the CO bonus if you apply for the SWA card simultaneously.