sounds like a decent plan. I wouldn't neccessarily go for a waterfall in my first tank, not that it's super hard, but it can add complications and it ensures splashy glass most of the time. even the drip in my 5.5 keeps the glass wet, and makes it harder to view. the ramp, I'd say, in a ten gallon, is a waste of valuable space... the frogs will be able to climb a few inches of cork. but if you have an idea in your head, go with it. I'm just generalizing.
foam may be more accessable, but it's such a long process, and if you screw up at the end, it can be hard to repair. the cork is natural, works well, is easy to use, and looks good. you can rip and break it with your hands, cut it with a knife or jigsaw, and yet it still holds up really well underwater. it's cheaper that using foam as well. you don't need to cure it, coat it, seal it, paint it, or any of that. you pretty much glue it in and wait for the glue to dry. plants love the stuff too.
for a ten gallon with the kind of sump structure you are into, I'd suggest getting one of the large cork tubes from herp supply, some plastic mesh, some ceramic filter media balls, a bag of cocofiber, and some fine dark gravel, (like flourite sized). you might need a bit of plexi here or there, but with those materials you should be able to do nice things. I like hydroton as a ceramic media, but it wouldn't work in my 5.5 gallon, because it FLOATS. so the minute I filled it with water, it just went to crap. keep that in mind! you want a non floating media for under the land.
the cork tube will be more than enough to fill the tank. you can cut it and break it to form your landarea's walls, and glue it in. then, fill the walls with teh ceramics, layer mesh over top, and add cocofiber mixed with a little of the gravel. (and some carbon if you have it)
the waterline needs to stay below the cocofiber, so plan for that with your wall height and layering.
you can use the rest of the gravel on the floor underwater.
also, buy some java moss now, and stick it in a jar in the window. cut it up a bit. get it growing, so when you're done building, you'll have some to work with.
in terms of filter, my 5.5 was cheap up until i added the locline. that stuff is great, but it's pricey. and the pump clogs every 4 weeks or so. it's not the best filtration. if I had it to do again, I'd just give myself a little more space back there. it's hard to get my hand in, and there's not enough room for more foam or anything. I worked up this idea, and think something similar could work well for a 10 as well...
http://www.aquariacentral.com/forums/showthread.php?t=201578&page=3 but it's unproven as of yet.
a canister filter will work well, but you might have a little trouble getting it primed the first few times. The canister on my 15 struggles to get started with the added lift. a lot of internal filters will work on their sides, but can be hard to obscure. if you have a dedicated stand for this, and the tank is used, drilling it out and having a sump under the tank would be awesome for this kind of design... but a lot of work. I've never really had a sump myself, out of space.
