Hi littleharp, it sounds to me like so far you're doing everything right, educating yourself about the illness and being as supportive as you can is exactly what we need from our friends and partners.
As to other websites, this is the nicest community I've found and there is a whole section for Friends and Family, which has some useful tips posted, as well as the rest of the board for you to use. There are some good sites such as
www.mdf.org.uk for basic information but it sounds like you have gone a bit beyond that, there are many books on the subject including a couple by bpbabble members, Jane ("The Rookie's Guide to Bipolar Disorder" and "Sugar & Salt") and Clayton ("Meds and Reds") which might be worth checking out if you can.
Welcome to the boards,
Cathy :-)