like toefl, ielts (for English) or hsk (for Chinese)
Oo, you can get certified in proficiency with a test offered by ACTFL: http://www.languagetesting.com/oral-proficiency-interview-opi
Evone is right.
There is no Tagalog Language certification, you need to have a Baccalaureate degree (Bachelor of Arts in Linguistics which is a 4-year degree program). In the Philippines, I believe only the University of the Philippines in Diliman offers this academic program.
I don't think there's any standardized one that is officially recognized here.
I think none, just a college diploma if you took Filipino major.