If you want the most options and ease of editing, you should consider an HDV (tape) based cam such as the Sony HC7 or the Canon HV20, both very popular right now. Based on what you said about editing I'd recommend one of these. And they use the same inexpensive MiniDV tapes that you're using right now and can be found anywhere. You don't need special "HDV" tapes.
Other formats may be attractive but depend upon what you want to do with the video. If you want instant playback and don't plan on editing, you could consider the DVD based HiDef cams, such as Sony's UX series. If you are okay with bringing a laptop with you and constantly copying to your computer -- their HDDs fill up in seven hours or less -- and still plan on not editing, then the SR series could be a good choice. But note that editing software support for these cams isn't as widespread as with tape. The full edition of Vegas, as well as Pinnacle and Ulead, apparently both will edit AVCHD files, which is what the HDD cams store their video as.
In terms of editing software, you should stay with what you know and like. I use Adobe Premiere Pro, which I find does most things pretty well. Many others swear by Sony Vegas -- there's a full Pro version and a more affordable version called Vegas Movie Studio Platinum that many people like and is well under $100.
Others swear by Pinnacle and Ulead, but on the other forums I read I tend to see more people complaining about them than liking them...
If your Mac is to be your primary editing computer, you could also consider Final Cut, which has passionate fans everywhere.