Firepower looks good. Note you could still kit one squad out for CC with a hammer to go with the Watch Master
Getting to the other side of the battlefield on foot though... that's going to be an utter pain. Hrmm. No drop pods, suppose one squad could deploy from the Corvus... If you have one available, finding some points for a Rhino or Razorback would help immensely, I think. Rhino's probably plenty, seeing as how you can fire the heavy assault weapons from the hatch.
Mind you, I like my infantry mechanized. YMMV.
In my army i have enough units to make 7 Veteran Squads. One devestator Squad, 9 Termies, 4 Vanguard, 5 bikes, 1 Watch Master, 2 Captains, 1 librarian, 2 Razorbacks (1 twin lascannon 1 Lascannon, twinlinked plasma gun) A dreadnough with multi melta and of course the corvus Black star. Just to give you an idea of what i can mess around with for this listing.
Problem with adding a guy with hammer, and other close combat weapons is that in the end they end up being worth like a squad and a half on their own which really drops my body count, on top of that to get enough points for the razorback i'd have to drop a infernus and frag cannon and a stalker just to get it.
Also now i got the codex with me, the list i got there actually ends up being like 1100pts so i'd have to drop some more again
Essentially some things i feel i need to have is the Corvus as it'll be able to handle troop hoards with the cluster launchers and twin hurricane bolters, plus it can aid in any tanks with the twin linked lascannon and is able to survive for abit longer with the re-roll jink. I also want to take my Watch Master with me as he is the icon of inspiration, the go to guy when it comes to extruding sheer greatness to cheer up any depressed deathwatch player's day. Other than that i think i should take at least some terms and 2 either frags or infernus so i can swap between some kill team setups as needed without actually editing my list then and there (which i'm pretty sure is an illegal thing to do barring having some pts over). Other than that really anything goes for what i'd do
EDIT X2: So really by taking those things with 2 squads (all bolters asides from the 2 heavy weapons) the two termies all default kit, the Watch master and Corvus with relevant upgrades will cost 740pts, no including any additonal stalker patter guns, flamers, meltas, rocket launchers, Black shields etc.