Hello i was wonderind what file format the zbrush progam uses
It uses it’s own format.
It can also import/export obj, dxf, jpg, tif and psd in various situations.
i recommend export your base mesh as an obj file from whatever program you’re using into zbrush.
as for textures, alphas, bump, displace; zbrush can read psd, jpg, and tiff, i prefer tiff myself cause it allows for higher res.