The pre-approval is legit. Not a guarantee, but as close as they come in credit card land. As far as limits, they are not nfcu. It seems like most people get an initial limit in the 5-10k range. They gave me my highest limit (7k), and I see a lot of people whose only card above 5k is usaa. If you are interested in their insurance, there is a discount if you have one of their banking products (cc, checking, etc.). If you don't plan to use their checking, the cc is a great way to get that discount.
In wallet: Ink Plus 10k, AMEX TE 25k. In bag: CSP 16k, USAA WMC 15k, Hyatt 13k, United MPE 12k, AMEX HHonors 3k. In SD: Cap 1 QS 5k, Discover IT 7k. FICO 08 says my EQ is now 844, was 510 in 2010.