what would the plot of reach ODST be like?

i havnt played halo 3 ODST however i plan on getting it and i know the campaign story and it sounds awesome. but what would halo 3 ODST be like campaign wise?

here are some things to ponder

1 who would you play as? im thinking whoever rookie replaces and that person probobly dies at reach

2 what would happen to them before and after new alexandria?

here is my thing, after sword base they get deployed to the bierei… biery… uh screw it i cant spell the name of the territory. basicaly when tip of the spear is going on they get deployed from graphton to the ground and begin to fight towards one of the other spires, basically you fight towards one of them with the help of UNSC ground forces. you get to the spire and download covenant data before turning the cloak off and once it’s finished the other spire six gets to is destroyed and the covenant super carrier appears and they turn off the shield and a falcon picks them up and takes them to new alexandria(before six gets their) and you help with the evacuation. after one mission in new alexandria buck gets seperated from the squad and meets veronica who buck gives the covenant data to and than they fight to a pelican where veronica leaves reach. next mission is after the covenant invasion fleet appears and they fight throughout the city again however this time at the very bottom of the city instead of in the skyscrapers. you fight to the ONI building where you get briefed by holland and he tells the squad he wants them to steal a covenant carrier. than the next mission is the same time six is in the falcon and you eventually meet as buck tries to get onto the covenant carrier. you get on and fight to the controll room where you use it to get out of the city but the carrier is chased by other ones and outgunned your character who gets replaced by rookie flys the ship while the others escape via covenant drop pods. than the others fight towards a evac site for UNSC personell and they get to another contenant where a ship is waiting to pick up and evacuate as manny civilians and UNSC personell. during this mission you meet gauntlet red and echo team and you all get to the ship and manage to get out allive except for one spartan team (gauntlet or echo since red is to cool to kill off)

what do you think about this and what are your own ideas?