Even though I know little about flasking and even less about what roths like, I'll toss in my two cents (careful - you get what you pay for!)
Sphagnum moss actually has natural antibiotic properties that minimize bacterial and fungal problems. I've never heard of the need to sterilize it, and in fact nuking it may well neutralize its antibiotic ability. Don't know. Use New Zealand sphag - it's the very best (although I'm sure Australian sphag is lovely too) and the plants can tell the difference. Must be the accent...
As for speedy growth, it's got to be about making the plants as happy as possible. This is not, 'if a little is good, a lot is better.' I love sunlight (particulary as I wait for 4 feet of snow to melt!), but I wouldn't want 24 hours of it every day. Too much sun will stress the seedlings and slow their growth. Same for heat, water, fertilizer, etc. There's a 'best' amount for each factor and too much or too little will slow growth. The trick is finding what the best amount is.
Oh well, that's the limit (and then some) of my knowledge on this thread. Alls I can say is, I admire your patience! I possess none of it! Good luck!