'96 Series II SC Freeze Plug Replacement

I bought my car last August and it has always run a little bit on the hot side. I have had other "higher order" issues to deal with first, so now that summer is coming I want to flush and fill the radiator as a first step. I was reading a review of Prestone Flush and Clean and the reviewer mentioned that his freeze plugs were so corroded that the cleaning process caused one or more of them to spring leaks when the rusted material washed off.

All of that to get to my questions: If this happens to me, how hard is it to replace the freeze plugs? There are four - correct?

Thanks in advance,
Joe M.