Well, to answer your question (not in order):
1. Nickel and diming.....Visual voicemail-get google voice, its free. Ringtones-try mabilo or zedge, they're free. VZNavigator-google navigation via google maps, its free.
2. Wait for EVO....im assuming you are talking about the HTC Merge. Not going to be much different than the SF, EVO, or Incredible. Just review all 3 phones and see which suits you best.
3. Bugs.....all phones have bugs. Each forum will have its fair share of bugs. Patches/updates tend to fix most bugs, but of course we will always find more. Just research the bugs you are referring to and see if there is a work around that suits you.
4. BOGO on SF. Well, thats a good deal. On any android device IMO. And, just so you will know. Its not just a BOGO on the SF. You can buy a Fascinate and get ANY device equal or lesser value for free (after rebate).
5. Getting SF at BOGO or getting discounts thru ATT. Well, the SF BOGO will help you at the point of sale to save money, but could you possibly save money in the long term with discounts at ATT? Make a good business decision on that one. And as you know, compare networks/plans/features etc..to see what your best value is.