Ok last bit first :
There isn't a difference, so much as a purpose for the straight and slanted. You wouldn't built a stack with a slanted one, then straight, THEN the head would you?
It's designed to be Straight - Slant - Head, so it fits together like that.
Now - Amps. I personally use the Marshall AVT Series Cab which is pretty badass, and I have a shitty Marshall MG head (one of the first ones with built in shitty effects) and it's ok, but sound wise it's pretty generic and doesn't leave you many options - but the reverb is pretty awesome.
The cab you looking at is fine, just remember it's the TOP cab so don't put anything other than a head on the top. Marshall do a hench range of heads, you should see if you can get an AVT half stack.
Go to the Bay of E - and search this : 130689691084
Thats what you want, comes with a standard channel changer footpedal with reverb (i think)