Welcome,although this should probably be in the "army list" section ,I'll go ahead and try to help you out a bit.
First,I'm assuming your 21 Plague Marines are split into sqauds of 7,how do you have them armed?,IMO a champ with a power fist is an obvious bring in you PM sqauds.
Second,Typhus is a gak load of points in a small army,do you have any other HQ choices?,a DP might be a better choice for you.
Third,one Rhino is going to get shot to pieces,you need more.
Fourth,you are aware that there is a 1 in 6 chance your Dreadnought will go insane and fry your own troops with that multi melta,a risky bring.
For heavy support,oblits are good,and IMO so are vindicators and predators,Plaguebearers are good tarpit units for cc.
Really could use a bit more info on your army.