1) apply from Hong Kong? 2) 10 y. L visa

Hello,

I'm Canadian already in Asia. Can I apply from Hong Kong for the L in Mainland China or it must be from my home country - Canada?
Also, I want to apply for a 10-year L. I was told Canadians can. If I decide to work in Mainland China at a later time, I have to apply for a work visa. Will the work Z void my tourist(L), meaning I must redo the same process to acquire a 10 year L after my work Z ends?

Thank you:)
Best regards,
Nic