Do you only have the 3 broadsides or can you field more of them? I always have more luck when I have 2 units of broadsides, even if it means splitting up one group into a smaller group. On the downside your giving your opponent the opportunity to get an additional
VP in Purge the Alien, but the positive is that you have two firing lanes and it takes two melee combats to loose all of them. Definitely bring the hammerhead. Since they changed jetpacks to
2d6" move in assault harrassing strategies with crisis suits got a bit riskier. The last game I played vs Chaos saw my deepstriking crisis suits wiped out the turn they arrived after laying only 1 wound on his
HQ. I also found my firewarriors were ok against his nurgle marines, but they seemed worthless against his demonprinces.

invulnerable saves. Point is
ymmv with firewarriors.
I'm not sure how you want to equip your crisis suits since you listed 3 weapons for 3 suits. You would have to equip them as twin-linked X + one Y on each suit and you'd have each suit with a different twin-linked weapon. The only problem with doing it this way is you have to hard-wire the multi-trackers and I think only the team leader can have a hard-wired piece of wargear.

You could add stimulants to your
HQ to give him
fnp.
I'd consider putting a seeker missile on the hammerhead. A
str 8 hit will bypass his
fnp on models with T8. Granted its only one shot but if you find a sole nurgle marine on an objective near endgame it might be just what you need to take him out, but that's just me.
Final note, consider bubblewrapping your broadsides with kroot or a squad of gundrones.