Share psd files without giving away libraries

"If I give someone else one of my psd files to work with, do they get all my pattern library, brushes etc?"

No unless you have applied pattern as layer effect or separate fill layer in which case pattern, gradient, layer style or fill layer must travel with your PSD file. If you provide your client with raster layers to which is pattern applied then he won't have access to duplicate or save your seamless tiling pattern.

Brushes does not travel with PSD file.