so, what captive bred fish, inverts, corals, anemones and live rock are there available today?
Seems like fish, corals, nems, and shrimp have already been covered. I want to add though that in the invert area, outside of shrimp, clams, a couple abalones, and a few types of conch, you'll be hard pressed to find aquacultured/farm-rasied or tank-bred animals. Hermits, most true crabs, and the commonly sold Turbinid snails are among those that are not captive bred or farmed on a commercial scale currently. That's not to say there isn't an ongoing effort to change that, but the effort hasn't met the goal yet. For snails, there are occasional success stories from individual reefers, but for most marine hermits I have only heard a couple of sketchy anacdotes with no proof to back up the claims.
The reason I bring this up is that a lot of store employees who don't live and breath the hobby themselves simply don't know where the animals are coming from and may not know how much is wild-caught. Similarly, people who are out to make a buck may give you misinformation if they get the impresion that it will make or break a sale.
EDIT: forgot to add on live rock, which I don't think was covered - you can create your own, colonize non-reef rocks, and/or get man-made stuff that's been colonized. None of those will have the same biodiversity of rock that has at least been farmed in a small patch of ocean, but it will do the job as far as waste management.
2, is it advisable to filter a Marine tank with a cannister filter system, as opposed to live rock?
I would never recommend a canister instead of live rock, just because it'd be pretty hard to put enough media in a canister filter to match the filtering capacity of standard amounts of live rock. However, there's nothing wrong with a canister AND live rock. In fact, that's exactly what I've done for my sump-less 55gal (one canister for chemical media and one for extra rocks) and it's been working great so far.
I dont use a canister filter as they have the tendancy to become nitrate factories.
I find the term "nitrate factory" to be a bit misleading, since it's often interpreted by those new to the hobby to mean something that suddenly makes more nitrate than would exist if the piece of equipment was removed. Since you'll only get as much nitrate as you have ammonia/nitrite to start with, it's really down to how much source waste you have in the tank. The main issue with canisters is that they present a good place to trap debris and that people often let canisters sit unattended until the flow visibly shuts down (whereas the same waste might get siphoned out or consumed faster if it's in the main tank). So, it's possible to get more uneaten, decaying goop accumulating in the system than you might have otherwise if the canister isn't given enough attention. It could give an ammonia or nitrite spike as well depending on what other filtration is around.
At any rate, there is an easy solution: add a prefilter and trap the goop before it gets inside the canister, then give the prefilter a quick clean at water changes. The inside of the canister will stay essentially gunk-free and provide nothing more than an extra body of water to house chemical media and/or rock. The prefilter will also become a scavenging area for small animals interested in those little tidbits that would otherwise be sucked away. Another added bonus is that the intakes become protected for fragile animals (nems, sea hares, cucumbers etc.). The only downsides I've seen are that it does add one more thing to do at WCs and I've had to use cut-to-fit filter pads rather than sponges. Sponges may work in some tanks, but large gastropods and sea urchins seem to have a taste for them.