Damn, I've never even heard about the spartan assault tank, but it looks cool!!
Anyway, mostly this list seems ok. But in one unit you've made almost all the mistakes there are (sorry, I know it sounds harsh).
The Sternguard. 1) 5 of them won't make it foot slogging.
2) I would anyway use 10 of them if you have the models.
3) They benefit from their Special ammunition so don't take special weapons for them unless you have to. (Combi-weapons are exception)
3) Their primary use is "alpha-strike". Simple. Put them in Drop Pod, give them combi-meltas, drop them near some tough enemy tank, take First Blood and benefit.