Hey Rob, come by if you get a chance and I can go through all the plumbing with examples for you. Really easy stuff.
Anyway, I'll answer what I can here, sans live examples:
They are, but if you get the chance, upgrade to a
proper skimmer. A properly sized Euroreef or ASM skimmer will knock the socks off of any two, even three hang-ons put together.
I'm going to strongly suggest that you skip drilling the bottom of the tank and instead install a side overflow. This is pretty easy, just get the glas cut for a box, drill 1.5" holes in the back (that's right, hole
s, you'll want two - more in a bit on this), glue in the box and install bulkheads. Drilling the upper side of a tank doesn't comprimise the structural integrity of the tank, the same is not true for the bottom. Ideally, the overflow box should be 12" long, 4-5" wide and 8" tall for best results.
Now for the two holes. Using two holes will allow for a silent overflow, check Keith's (andrewsk) thread for more info on this:
http://216.187.96.54/vbulletin/showt...t=25427&page=8
The basic idea there being that one hole (the one with the standpipe) acts as an emergency drain in the advent that the main drain (the one with the grill) clogs. The main drain has a valve at the exit that you throttle down just until the water level is a bit shy of the emergency standpipe. This keeps air out of the main drain while removing the drop that the water takes in a normal overflow. No air in the sump + no waterfall effect in the overflow = Silent system.
For pumps, I'm going to strongly recommend that you have your sump customized with a 2" hole at the return end. This gives you access to external pumps. External pumps > internal, no questions. No heat transfer, lower head-loss rates, easier to access and maintain (use true union valves when you plumb), lower noise issues, there really is no reason to use an internal unless you're limited by space or budget (the cost difference is about 25% for comparable pumps, with the externals being on the higher end).
You'll probably want to run anywhere from 500 to 900 gph, pending on how much flow you're going to get out of powerheads/closed loop within the main tank itself. Lower flow from main tank to sump being better (allows for a longer dwell time, a plus for skimmer performance). Since I'm at it, I'll also recommend a pump for you too: Sequence Reeflo Snapper. 500-2400 gph. Super silent, ultra reliable, plumbs with 1.5' tubing (AWESOME) and has a
THREE YEAR WARRANTEE!!! The price is right too ($230-$250 CAD MSRP). The only down-side being that they arent pressure rated, but that's hardly an issue if the sump is directly below the tank on the same floor.
That's proper thinking when it comes to this hobby. All the newbies take note here :P
It could be worse, you could be asking zero questions.
Hope that's of help. And like I said, drop by when you have the chance and I'll go over the nitty gritties of plumbing with you step-by step.