I had to provide proof of veteran status (I have the indicator on my drivers license but an ID card or DD214 also work). Don't know if you need to bring the old plates to get new ones issued with the same number. I didn't care about keeping the same number so I'm just getting new plates.
You paid sales tax at purchase time along with some documentation fees for getting the paperwork to the state. Ownership tax is different and paid each year. Fortunately, it declines quite a bit after the first few years as shown in the link provided by
@Avrana_Kern.