From what I have seen in various Halo media, I can conclude the following about the makeup of an ODST squad.
Squad consists of 6-8 members, slipt into fireteams of 3-4.
Customisation of armour is limited, only "elite" squads (such as that in ODST) gets personal customisations outside of what can be provided by the UNSC (flashlights, VISR, UA helmet attachments...)
Weapons are, in a 6-man squad;
4 Battle rifles,
1 Assault rifle or sniper rifle,
1 M247 or similar machine gun.
Secondary, mission specific weapons would be;
4-5 SMGs or Shotguns,
1 Grenade launcher or Rocket launcher
All members are equipped with a knife and an M6 of some variety with limited ammo as a last resort weapon.
These can be changed dependant on mission.
3-4 sqauds to a platoon, 3-4 platoons to a company and so on.