OK, now i see what you are talking about regarding update folders. Usually, a dev will wait until they have major changes to make to a ROM before they update it, unless there is some issue that is popping up, and they have a fix for it. These updates, or flash overs, are also easy.
Just make sure it is actually an update, and not the whole rom, then open ROM manager and install from SD card as before, but this time DONT choose wipe data/cache, because it isn't a full rom.
As far as HTC account, when you load a Z rom, the first thing you should do is create an HTC account, I just used my gmail address. then it syncs the phone, and next time you wipe data/cache it will basically restore most of your apps and some other settings. It is very easy and seems to restore the phone quicker than AOSP ROM's