Terminators are quite good at assault and all that, but the real power of the terminator is the "Termicide" unit. make two groups of three or four, combi-plasmas or Combi-meltas, and Deep strike them behind enemy vehicles/MC's and pop them instantly. Your squad of terminators is pretty much Overkill on the assault, and will end up dominating a combat, and then getting shot to shit by the nearest group.
I'd put the plague marines in a rhino and run 7, with 2 plasmas and a champ with a fist as you have stated there.
CSM standard troops with a Icon of Chaos Glory is actually pretty BA in combat. They will pwn hard if you can get them into the fray. They also shoot pretty well.
If you drop the terminators down to 2x3 Termicides, it should free up some points for another plaguer, and a rhino. Toss the marines in the landraider, plaguers in the rhino and send your Prince up the field behind the landraider as cover.