ok ill try to do every point seperate:
firstly fuel rod cannon grunts are basically the anti tank weapon, and they are limited to one per squad so that seems fair.
I will put an option for grunt squad being led by elites/brutes, i havent worked out how im gonna do their command system yet so i didnt give them leaders at all till i sort summat
next, they have the option to upgrade to snipers, but in a full scale war i'd see them in bigger squads than 2, i may reduce the minimum size to 2 for fluffy armies.
i only reduced the maximum squad size to 5 for brutes because i dont remember ever seeing more than 5 at once, and to fit in with the prowler when i make its rules, as in the game it can only hold 3, but ive stretched it to 5 because of what ive read in books.
yeah the gravity hammer thing will be sorted, i was just trying it out as i didnt think 1 would be enough lol, itll be changed
all units that are missing will be included eventually dont worry, i just nhavent got round to it yet
and now onto the UNSC:
i didnt include those weapons as they'd serve no viable difference in game other than having crap range. if you want just use the smg as a morita carbine.
??? spartans are in the list lol, theyre after the warthog
the elites thing will be a sub rule later on, as will animosity between brutes/elites and grunts/jackals
hope that helps, and thanx for your suggestions, some will definately find their way in
edit: ooooo its designed to allow fights from any time period in halo, even what if scenarios