An organist
An organist
A guitarist.
A bassist
a harmonist.
a guitarist
an "accordionist"
If you are talking about a pipe organ call Lewis and Hitchcock 301 931 2374. If not, call them anyway and ask them to recommend someone.
lute player
lute player
Call them anything you like, they won't answer back!
An athlete
It is called a solo. The texture is called 'monophonic' texture (it means "with no accompaniment").