Do I need a visa even if I have a ARC & ROC passport?

Here’s my situation.

I’m American and my parents are Taiwanese. Last year I applied for my ROC passport/visitor’s visa in order to enter Taiwan to apply for my ARC. Now that I have received and held my ARC for over 183 days and my visitor’s visa on my ROC passport has expired. Do I still need a visa (visitor/resident) on my ROC passport in order to stay here? Or is a ROC passport with ARC good enough and I can stay as long as my ARC is valid?

Another question is, do I need to fill out any papers or report to an official in order to leave Taiwan for a short vacation? How about entering Taiwan? Will my ARC info show up when I go through customs allowing me to enter Taiwan without a visa?