Try this FORUM and it very handy ....... Dev shed also uses Vbulletin
http://www.devshed.com
You will find your answer there I am sure of it.....
Most HOST already HAVE PHPADMIN Installed it comes with the CONTROL PANEL.............
You must have some sort of CPANEL they are add ons for most host unless you have DEDICATED SERVER.... Which I doubt you sound clueless....
About CRON: I havent heard of anyone using cron for Vbulletin yet.... AND WHAT FOR?
Im still clueless