Should do a full soil grow first, then slowly transition into a part soil, part hydro, then into a full hydro (DWC?) setup. That way it gives you a stepping stone to learn. In 3 year's of growing I've never grown Hydro, probably never will. Been meaning to setup a DWC system but always proffered soil.
Your plants aren't doing that bad. They're actually doing fine. We really don't know what's going on with the 12 day old plant, it could be working on its root system for all we know, and one morning you might wake up to a massive growth spurt.
I've personally always found that If i keep my plants inside a small container *soil grow* (1L ish) they'll be single cola (1 massive cola) and flower faster than a plant say in a 10L or 15L container. In your case, this can be a really really big advantage. Because of the legality of Cannabis in VIC atm, <10 plants = no trafficking offense. So you could grow 5-6 small single cola plants (yield you 1 oz per plant, roughly.) and you'd break-even on all your equipment in like 70-80 days.
Goodluck with the hydro grow man. So far so good. You'll still get a bit of bud off of her.
ALSO -
Don't give up on the AGP. Never give up on a plant! That plant could totally surprise you and give you a nice ounce of meds. I would suggest using the soil mixture I PM'ed you, transplanting her, giving her a nice dose of SeaSol and putting her in your grow cabinet. Don't pay too much attention to her and just let her try her best to come back to life. It's a weed afterall, it's designed to live one way or another. Until the plant is dead and fallen over, there is still a chance it will flourish. Btw got any pics of the AGP?