No, you keep nothing that you acquire in the BETA.
You can build stuff in halo 3,halo 3 odst and halo reach.
Blood and stuff.
Because not everyone has Reach yet. And Halo 3 has dual wielding and other stuff Reach doesn't have
No but the XP you get in Beta will still be on the normal Halo: Reach but you will not keep the Armor or cR
Short answer: bad. In Halo: Reach the Elites (Sangheili) are fighting for the Covenant. This is rather confusing to many players as they were allied with the UNSC in previous Halo games, but keep in mind that Halo: Reach is set before even the first Halo game, Halo: Combat Evolved.
Probably, Bungie said halo reach was their last game... ...but Microsoft will probably keep on making halo games. Keep asking questions at Answers.com :)
Because they -the Elites- are taking over Reach, and you are trying to stop them. This is rather confusing to many people as they were allied with the UNSC in previous Halo games, but keep in mind that Halo: Reach is set before even the first Halo game, Halo: Combat Evolved.
although DST has a few more maps and some better stuff.....wait it out REACH will not upset
Because they -the Elites- are taking over Reach, and you are trying to stop them. This is rather confusing to many people as they were allied with the UNSC in previous Halo games, but keep in mind that Halo: Reach is set before even the first Halo game, Halo: Combat Evolved.
If you mean sell armour to other people then no
I expect Bungie to keep the extras from halo 3 and move them to reach. So, to answer your question yes I think they will have double exp. weekend in reach.
If you have an Xbox live account, and you play Halo Reach while online, Bungie should automatically keep track of all your statistics. Halo Waypoint is one way to view these statistics.