Visa processing fee and time? Tibet travel permit for nepalese willing to go via Tibet To Nepal?

Hi there, I m a nepalese national doing my Residency in Neurosurgery here in Pakistan. I wish to go to China at the end of May for a conference.
- How much is the visa fee for me and processing time?
-can I obtain Tibet travel permit from pakistan along with the mainland entry permit?
- if not, What is the normal processing time for the permit when applied in Beijing? And the processing fee?
Thanks.