the X is call a double sharp.
is where by a person plays the note 2 semitone higher ignoring the diatonic key of the piece and playing it as it is refering to the note and ignoring all acidental infront.

Simplified, just play the note 2 higher, C play D
G play A
G# play A#
E play F#

picture cant be seen liao.

if got bass clef & treble clef together, means piano. cause violin cant play both part.

it could be played on a violin by just playing the treble clef lo

both treble.

And the way the song is arrange, its guitar