There are lots of different types of tea and much higher quality teas than what you'll find in the grocery store. I highly suggest not getting tea bags as they're generally full of dust and fannings. I also dislike "tea bag" flavor from standard bagged teas.
I highly recommend http://uptontea.com
I drink mainly black tea (usually iced), but the gunpowder (tightly rolled leaves) green teas might be a good bet for strong flavor (such as this one). Avoid jasmine unless you're interested in the scent & taste - it's very strong (but orange peel and jasmine might be interesting).
I'm not sure when the best time to add tea is, but you might want to try "dry hopping" too. You'll get very little caffeine addition without hot water (180 degrees F).
I can't comment on tea beer, just tea.