Don't get hung up on there being only 4 films. Slovakia has more villages than towns or cities. You would order a roll that covers your ancestor's birth year. If he was Roman Catholic than Plavnica's church records would show his birth and his parents marriage. I would recommend you find out his religion in his US church marriage record. You are darn lucky that Plavnica's church records cover years from 1683 to 1926. Some of us are not that lucky to have records go beyond 1800 for several reasons beyond our control. The only thing you have to fear is the priest's handwriting so than I would recommend hiring a researcher, which I have recommended in my other replies.