firewarriors: try
these, either stock or glue tiny strips of plasticard to the guns to make them more pulse rifle like.(as shown
in this thread. also shown are the microworld foundationist power armoured troops which make great stealthsuit proxies (if you're the kind of masochist who uses stelathsuits
)
Battlesuits: try
these guys for battlesuit proxies,
these might also work, although not sure of how well they scale as they're 15mm.....
these are 15mm too, but they might work
Hammerhead wise, you can still get skyrays from Forgeworld, with some ingenuity you can convert them easily into devilfish (cut off the missile racks) and hammerheads
(page 9 of this thread has some good ideas)
more discussion
here....
hope this helps!