i'm new to dnn but not to asp.net development.  in theory i love the time savings dnn offers to application developers and am starting to play around with the basic functionality. 

i'd like some help from those of you who have at least a little bit of experience.  i'm trying to choose between whether i should go with dnn 3.x (3.2.2) or 4.x (4.0.2) to launch my first live site that i will actually direct users to.  i have a few questions to frame the discussion.  ...and please, any and ALL feedback is greatly appreciated!

1) new vs. established-  since 4.x is newer (and intended for asp.net 2.0), does this mean it's less stable than 3.x?  is there more tweaking to do to get things up and running?  i've been developing with .net 1.1 for quite some time and to date have only dabbled in the 2.0 framework.  maybe taking on 4.x will be the prod i need to get me kick-started and knee-deep in 2.0.  how is the stability of 4.x?  also, how easy are 4.x upgrades to integrate both on a source and install level when new releases come out?  (ie is it 'once you install version 4.0.2, you're pretty much stuck on that unless you want to start over from scratch')

2) sql server- does 4.x run only on sql server 2005 or is it possible to run on 2000? 

3) compatibility- one of the things i'm pleasantly surprised at is the healthy developer community around dnn (specifically module development), but can modules developed for 3.x be used with a 4.x site?  if so, is there a performance hit for using that module?

let me know if you'd like me to clarify anything- thanks in advance.