Hi Kim, welcome to the forum
I'll attempt to answer some of your questions, and ask as many as you want, that's what this forum's for
I think a forum specifically for fish keeping terminology has already been suggested. Until such a thing actually comes about, try looking here:
http://www.zebrapleco.com/forum/viewtopic.php?t=539
There's some basics about water chemistry and stuff there.
You shouldn't have to ever really measure flow rate, as most of the filters, powerheads etc. you'll be buying should have that information right on the box. Usually it will be a measurement in gallons per hour. So, if you buy a filter or powerhead that says "300gph" it literally means that that particular piece of equipment will suck and return 300 gallons of water every hour (under ideal conditions).
To continue the scenario, say you put this 300gph filter on your 40 gallon tank. Now you have a 40 gallon tank that is "turned over" (meaning the total volume of water is passed through some kind of filtration) just under 8 times an hour.
This measurement is highly debatable, and mostly depends on personal preference. Some people on this forum turn over their tanks around 6 times an hour, others will do as much as 20. I know that sounds a little confusing, but I would suggest leaning toward heavier filtration, at least until you start to feel pretty comfortable with the fish you're keeping. Filtration can compensate for the mistakes everybody makes in the beginning
As for brands and such, I like the Aquaclear power filters. They are very easy to maintain and extremely reliable, I use both 70's and 110's on my tanks. Canister filters I tend to stay away from, as they can be a real pain in the backside to maintain, and are much more expensive. That said, I do also use a Magnum 350 (which I don't like). If you are dead set on a canister filter, I would say go for Eheim, they're really excellent filters, but again, very expensive. For a powerhead I would go for either an Aquaclear or a Maxijet, I have used both and they are very good.
For setting up your 40 breeder, I'd say you should aim to turn your tank over aroun 15-20 times an hour (again, just my preference). So, a good combination of filter and powerhead would be an Aquaclear 110 (500gph) and an Aquaclear 50 (270gph) powerhead. This setup would be a combined flow rate of ~770gph (19 times an hour for your 40 gallon tank).
A sponge filter is basically just a piece of fish safe sponge with an uplift tube and driven by an airstone. They provide excellent biological filtration and you may wish to add one to your tank. For these I like the Hydrosponge brand.
I hope this answers some of your questions
Val
I don't even know how you determine flow rate or how many times the water cycles per hour in your filter. So much to learn... 
