All of my research was done by a professional researcher from Przemysl who I hired last year after reading a recommendation here on an Ancestry.com forum. It was the best single move I've done since I started trying to trace my family ties. I had no information at all about my Polish ancestors other than my grandparents names, and my tentative hunches on village origins and birth dates, based on a few scattered and confusing documents from here in the US. Three days of his research work in the Przemysl church archives gave me fully documented data (births, deaths, marriages) on dozens of family members, going back several more generations
The archives are not on line. They're kept under close control by an archivist who has reputation of being somewhat difficult to deal with. I've not made a trip to Poland yet, but I really want to do that in the next year or two.