For all your DIY e-juice questions I recommend reading through the 3 blogs in my signature. Each focus on a different part of the process, from safety, to supplies, to your first mixes and recommended flavorings.
As far as Sub-ohming goes, it is becoming very accessible now. Atlantis, Kanger Sub-tank, and many others hitting the market, as well as many 50w devices that won't cost an arm and a leg.