Personally, I'd say use two fast AR's rather than the LMG. Use the LMG if you're a weapon specialist.
Honey Badger is actually a decent and fast reload weapon. So certainly use that. Have it with a grip and rapid fire, you will plow through your enemies.
I definitely agree with you #3. Vulture's just don't seem to last long, and even when fully upgraded, seem to fire about 1 rocket. Sentries last for quite a long time, and you have 2 of them!!!!
- On the escape, people go and set up their sentry guns at the first meteor. If there are some of you with 2 sentries, then have 2 of you take a sentry gun to the second meteor, just near that jeep with the turret on top. Place it at the side of it, facing towards where you will be running from. This will do 2 things: 1) Scorpions spawn right in front so your sentry guns will kill them, at least most of them anyway, and even some hunters. 2) it will help damage the rhino's that spawn. I actually some times put a sentry gun on the roof bit near the attack heli. You go up the stairs, and you can go onto the ledge, can't you. Place it just up there, it doesn't get attacked and destroyed, and kills the scorpions easily. I find it best to still have 1 sentry next to the jeep, and then one up here.
- To add to RareScotchFillet's #6 about propane tanks.. Most people stash them on the hive. Don't do this at all. They get destroyed too easily up there. In the Motel area, stash them on the left side of the heli hive, near the SMG, where that other propane tank is. That way it's in a corner, and out of the other hives views. So no stray bullets will get them. In the City area, throw them up into the building where the attack helicopter is. On the right hand side, there's a mattress or table on it's side. Throw them AT that, and you will see the tanks vanish. Don't worry, they are still there and you can pick them up. This is also useful for being at the heli hive, and one person goes up there and throws them down, the others throws them on the hive. So much faster.
- Rare's #10 is an extremely good and important thing you need to do. Even the escape is team work.
Haha I have had #12 happen so much. All three things you listed. I HATE when I am the only one trying a challenge, especially if it's the shotgun or sniper one. Even more so if they just keep stealing the kills from me with their AR's. Though, on the other hand of that, I have been in lobbies before where I am the only one who buys a shotty, for example, BUT my other teammates either can't afford it, or have the "no weapon purchases" relic on, or because they have already bought a weapon just before this hive so have no money. But, they run around and knife a scout once, then it's a one shot kill for me with the shotty/sniper. SO they don't kill until I have completed the challenge. That's always a nice feeling when you are just "ahh yay, they know how to work together".