#1
Okay i recalled one of my friend blew a fuse or something on his guitar.....

Is there any precaution turning on or off an amp before or after playing?
#2
there are no fuses on the guitar, but you can damage your speaker if you dont either turn off the amp or turn the volume down when connecting or disconnecting your guitar, the pop and buzzing can damage your speaker. Im not sure of the damage to any tubes.

Make sure all volumes are down when turning on or turning off or unplugging anything just to be safe.