I've been doing low-carb for 4 years. Not Atkins, but Protein Power. At the end of the day they are the same, but they start off differently. I suggest the PP book over Atkins because it explains WHY it works so you aren't worried about hearts clogging and stuff like that. Thanks for those links collington, by the way.
RE: potassium, starting off I took potassium & magnesium supplements, but not I seem to get all I need from the veggies I eat. My body has changed significantly. But bananas are SUPER carby and will definitely make you crave more sugar. I don't suggest it. One of the few things that even when I cheat, I avoid.
And oh, I lost 50 pounds. Feel great.
My best tip: plan cheats. I planned on, for a whole day, every 6 -7 weeks. Put it on my calendar. THat way when I looked at the muffin in front of me I didn't think "God I'll never have one again this sucks" I thought instead "Yep, *blank* number of days to go until I have one!"
I've found low-carb in England easier actually, not when it comes to specialty products like chocoates etc (a sad lack of it here, atkins makes gorgeous peanut butter cups in the US) ... a lot of ready meals are low-carb friendly. Meat, Veggie, & sauce. Of course, since I've already lost my weight I eat about 30 carbs a day, so I can have sauces like that - but you can't while you're losing weight. Slows it way down, but more importantly makes you crave a cheat like nobody's business.
Blah blah blah.