[Skahtboi]

Of the associations with which I am familiar, you can do just slowpitch, or you can do just fastpitch, or you can do both.

There is no real certification procedure, per se, to being an ump in most places. What you do is pay your dues to the national association and to the local chapter. Most all require that you take the ASA test in some form or manner, either as an open book test, as a test with the rest of the association, or in some cases, a closed book test. The point of the test is to make sure that you are familiar with the rules of the sport you are desiring to officiate.

I don't know if this answers all of your questions or not. I am sure that others will come along with more feedback as well