#1
I have an old Bass amp, A Yamaha G25-112. I don't play Bass, and the only reason I have it is because my Mom used to play bass around 15 years ago. I may trade it for a Vox AD50VT

Now should I, because although the Vox is a pretty decent amp, its still Solid State however. Should I bother with the hassle of it, because I was going to buy a Valve Jr next week anyways.

Can the Vox handle Early Metallica Distortion, and is a tube swap going ot give it more gain.
#2
the XL could, but i dunno about the normal ones...
a valve jr couldnt anyway.
with a pedal, the vox wouldn't sound good.
#3
I would keep the Bass amp, can always come in handy in a jam situation.
all the world's indeed a stage and we are merely players