I've got a Happy Traum blues book. Unfortunately, I suck so badly at reading guitar tab I can't use it, but I've heard good things about him.

Alternating bass is the "oom-pah" bass you get from alternating between two notes on beats (sounds like the typical Johnny Cash beat). Sort of imitates a stand-up bass.

Actually, I get "stuck" sometimes and have to stop practicing whatever it is that's "sticking" for maybe a week, and then come back to it. I think mostly I get frustrated, but a short break often helps.

Find someone else to play with, who knows a bit more than you do.

Learn to use a capo. D and A chords will kill your hand after awhile and don't have good bass notes; capo and play C and G. Also, work on learning to recognize chords when other people play them so you can practice chords in "real time". You'll only get a few of them per song at first but eventually it will sink in and it will help you learn to hear chord changes.