Advice on lens for Glidecam
Two things come to my mind: If you never operated or balanced a Glidecam before you will probably have a hard time. When using a Glidecam IS will not make such a big difference but nonetheless there will be one. So better have IS.

I am assuming that you are using a DSLR like the Canon EOS 5D Mk III.
Especially the 5D has quite good low light capabilities. Faster leses are generally speaking good but keep in mind that you need to pull focus manually and that you need several meters depth of field. So you might be good to go with what you have.