I would avoid advanced if your budget is of concern, I used them for several years
and now that I'm off of their product my wallet and my plants are thanking me. I currently
use Dynagrow as they have a great base formula that's super easy to use, and has all
essential minerals needed for great quality bud.
For aero timing I would stick with 1 min on and 4 min off. This has given me the best results
over 15/15 30/30 and some of the other cheap home depot timers. Ebay has many listings for
cheap cycle timers that can get you to 1 min on 4 min off. Just make sure you get one that is
grounded as many pumps are 3 prong such as this one:
http://cgi.ebay.com/Repeat-Cycle-Timer-50-Sec-Intervals-Aero-Hydroponics-/220788938469?pt=LH_DefaultDomain_0&hash=item33680bd6e5
They're also pretty cheap and I'd recommend picking up 2 just in case. I have had one die on me now,
which was my own fault, but was still nice to have a second to pop in and be going again. Other cycle
timers are in upwards of 60 dollars and do the same exact thing for 3x the price.
Seedlings will work fine in either of those systems, just be sure not to fry them with nutes
or it will pretty much devastate them. Start off slow and steady and over time you'll have
a good grasp on things.