Need advice on DWC setup

let me first say, this might be a thread already started, it's just not showing up though so not sure what the deal is.

So, about to venture on a first time grow, decided to go with a DWC approach.
I loved the simplicity of mogie's plan https://www.rollitup.org/do-yourself/...s-growing.html
and would like to to that.

I think we will want to get 2 of those setups with 4 plants in each. I read elsewhere that plants need 10g each, so maybe we should try to find a 40 g bin, especially if we want to grow a sativa hybrid later.

If we get a bigger res, and hold 4 plants, would we need another airpump and airstones?

I was thinking of 3 options:

we could just buy 4 of those air pumps from walmart, and use 2 (each with 2 of those little airstones) in each res.

OR

could get 2 of these more powerful pumps, one for each res, http://www.htgsupply.com/viewproduct...roductID=50477
and have 4 of these airstones : http://www.htgsupply.com/viewproduct...roductID=51881
2 for each resevoir.

OR 1 of these http://www.htgsupply.com/viewproduct...roductID=51179
then wed save space using just one electrical plug.

I would like to do what he did with the tubing, using the t valves to make it so only one tube goes into the res, but I'm confused about the sizes. will those t-valves shown below fit that tubing. and do all airpumps fit with 1/4 inch tubing?

I was hoping to get this tubing: http://www.htgsupply.com/viewproduct...roductID=50503
and some of these:
http://www.htgsupply.com/viewproduct...roductID=51764

also, are EC/TDS meters that important? they are hefty expensive and we've already spent plenty of money. I know ph is and we have testing strips and ph up/down solution.

Thanks