Insulation, Radiant and Vapor Barriers - attic insulation

I live in the deep south and have bought a house with a nice floored attic which I would like to build out one day. However, there is no insulation and rather than tear up the flooring I'd like to put batts on the underside of the roof in the rafters. R 30 has been recommended and the rafters are only 6 inches wide. I have a couple of questions: 1) Does anyone make R 30 batting which is less than 9 inches thick and if not do I add wood to the rafters to make wider or go with a lower R value (thinner batt)and try to blow some insulation under the floor? and 2) Do I need to leave a 2 inch gap between the insulation and the underside of the roof or can I put it flush against the roof?

I have never done this before and I appreciate any tips anyone can give.

Adding the insulation to the rafters would be a mistake in this case. You want the insulation between the ceiling joists so you aren't heating and cooling your attic. Lay the R-30 batts over attic floor. You can always pull them up if and when you finish the attic.