I haven't used 2oz fabric to be honest but i did get a few (free!!!!) samples fromhttp://www.ebaystores.co.uk/iwantfabrics
and it looked pretty good for the price, good for a first build (imo) where it's hard to justify the comparatively huge price tag of Icarex. I am using the 48g stuff myself and it suits my purposes well.
For spine reinforcement i use a clear reinforced tarpaulin (you'll find tons on ebay) just get the lightest you can find. For standoffs ..you can always use dacron.
Im no expert but hope this helps