Govt/Pvt/Int Schools Query

I have been trawling through forumosa and the Internet about this issue but cannot find a clear answer.
My husband and I both taught in Taiwan at a buxiban so we are familiar with that system. We had our fill of that, returned home and obtained teaching qualifications. We wish to return to Taiwan to work for government, private or international schools. My question is this: why does it seem we cannot enter Taiwan on work visas? An agent who has been in touch with us has given us the usual bit about having to enter on a visitor’s visa which then gets converted etc. But I would assume that if we work for a government school, why do we have to enter the country on false pretences?
Also, I am South African. Previously I simply submitted certified copies of my degree and certificate. The agent says that I need to have these documents notarised at the Taiwanese Embassy now before I come to Taiwan. He says this is due to a new regulation in Taiwan. Has anyone heard of this? We were in Taiwan from June 2003-December 2005.
To the forumosans currently teaching in government/private/international schools, is it standard practice to give a demo for these posts? I had a government school contact me and want to set up a demo via webcam?! This seems odd. Any advice, suggestions, comments and or input from teachers in these schools would be appreciated.