Basically,
Yes and yes. To go from a 1.0 to a 2.0, its rear drive line and chassis, though the 2.0 radio tray is reccomended. All other parts from the 1.0 will work.
2.0 body will fit a 1.0 with no real issues, the rear body mount hole has to be trimmed a couple mm's towards the front of the body to allow some flex.
1.0 body will fit the 2.0, the rear body mount hole has to be trimmed towards the rear of the body to allow flex. That could make the rear of the body weaker than normal.
2.0 rear hub hinge pins will work on the 1.0 hubs if they are drilled out to 3.5mm. Many guys I know use the M2C hub hinge pins which require drilling.
2.0 rear bearing inserts for the rear gear box will not fit a 1.0 gear box.
Arms are the same front and rear, though the 2.0 arms are a little stiffer.
Probably alot more that I am forgetting, but I am sure guys will point those out.