Current data looks more like:
60% on 2.2,
27% on 2.1,
1% on 2.3*,
6% on 1.6,
5% on 1.5
So with 2.1+ you reach 88% of the market. 3.0 is for sure something of the future, but only available for tablets right now - developing exclusively for it will leave all the mobiles out for a long time.
The graphical layout editors get better and better - I did not have much luck when I looked at them 9 month ago, but the situation has changed.
I'd propose to look at them and use them - and then a) have a look at the results and b) optimize the result if the graphical editor's is not what you want.