Be reassured that ABG's are a worry to many and I believe that even many MD's do not fully understand the info they receive in ABG's. I sometimes go to www.nursingnet.org
and they have a student nurse BB, too. An RT was advising folks that he could teach you "all about" ABG's, too, so you might try that out. I have a feeling he will give you more respiratory than metabolic info, but RTs are a good resource, so give him a try.
I don't have any great resources for ABG's though.
Now ECG's; there are so many great resources out there that I would just encourage you to go out there and find one. A classic that I think is still in print is called "intensive coronary care" by Meltzer, Pinneo & kitchell. My edition of this one is so old, that Verampamil isn't even mentioned (calcium channel blockers weren't yet invented), but it is a very basic text and doesn't overwhelm you and I think later editions of the text retained that quality. Just remember, arrythmia interpretation occurs in the context of a patient situation. Or as an old doc I knew once said, "when in doubt, treat the patient."