Collocations for choir - noun

massed (esp. BrE)
a massed choir of local schoolchildren

50-strong, etc.
ladies', male-voice, mixed, etc.
youth
college, school
cathedral, church, etc.
gospel

be in, sing in
She sings in the church choir.

join
conduct, direct
accompany

perform, sing

practice
Choir practice is on Wednesday evenings.

director
member
concert
loft, room, screen

in a/the choir
two of the girls in the choir

be preaching to the choir (AmE,figurative)
I realize I may be preaching to the choir (= telling someone who thinks the same), but I think he's gorgeous.