*most* people would agree a 510 or ego/Tornado are good units to start out with. an ego or Tornado is basically a 510 with a bigger battery. Batteries only discharge when you are pressing on the button to produce vapor. A charged battery should retain it's charge for at least a few months if it's unused.
A standard 510 battery will last you 1-2hrs of moderate vaping, a mega battery might last 2-4 but an eGo/Tornado battery would last you much longer (your mileage may vary). If I were to start vaping from scratch, I'd go the eGo/Tornado route. A bit more $$ to start out but compared to regular smokes, it's a drop in the bucket.
You'll get used to refilling, etc extremely fast. The first day or two you might spend tinkering and figuring out what methods work best for you then everything will become second nature.
Christopher - damn you for typing faster than me.