The only way to know is to try.
No
No
No
No
no a 250r motor will not fit in a 200x frame but it will fit in a 250r frame
There is a small double ridged blued sliding latch on the bottom of the receiver just behind the forestock. Pull/slide it rearward and the forestock drops down about 5 degrees. With the forestock released this little bit the barrel can be removed from the frame. Then slide the barrel forward out of the receiver. The forend does not disconnect from the frame without further steps. Reassemble in the reverse order. Be sure the barrel is oriented so the lug on the bottom middle of the barrel fits/slides into the bracket fit on the forend.
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No
no
No
No it will not
To install a pocket door frame, first, measure and cut the opening in the wall to fit the frame. Then, assemble the frame according to the manufacturer's instructions and secure it in the opening. Install the track and rollers for the door to slide into the pocket. Finally, hang the door on the track and make any necessary adjustments for smooth operation.