My new 225ltr venture!

I apologise in advance, I want to be as consise as I can! For three years we (well, I have done all the maintence etc) have succesfully kept a 30ltr tropical tank and have now bought a 225ltr tank. It was sencond hand and cleaned it with a water and vinegar as I was told was suitable, rinsed the hell out of it and leak tested, we seem all set to go. As this is a whole new venture, I want to make sure I am starting out the best I/we can.
Equipment I have so far chosen are 2x 200w heaters (interpet probably) and an Eheim Ecco pro.
Rather than going out and buying plants here and there from the two decent shops to select from in Aberdeen, we were looking to buy the following; http://www.onlineaquariumstore.com/a...ollection.html
After lots of research, ThinkFish as my primary source, the comunity we are looking to build to so far is; penguin, black phantom and neon tetras, white cloud minnows, marble hatchets, 2x angels and a few japonica shrimp. And also my new colleagues yet to be identified bottom feeder from her tropical tank which she is giving up (brown stripes, about 7cm long so far)
Now, I have two main questions. firstly, I am unsure which substrate would best suit the fish and plants? I have been looking a pea gravel, though I do not know when sand is most suitable or the planting substrate.
Secondly, when I trailed my partner around to check out the competition (which wasn't that difficult I am afraid to say), one shop advised my partner that we could happily keep a blue lobster/crayfish in the tank we were intending to keep. This seems to conflict with everything I have read. And also that we could get hermit crabs, however I can only find info on marine hermits. Could someone please help me, as my partner is now convinced that we should get a crayfish and/or crabs for our tank, and I feel like fish will end up as feed!
I would be extemely grateful to anyone who will pick apart the plan and put me straight, and all suggestions appreciated!
(BTW why hasn't Practical Fishkeeping got back up yet? I was advised they had a security problem 04/12 and that the website would be closed down until further notice!)