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.
No
No
no
No it will not
No
no