Berry, I missed some of your post. Most of the time it isn't necessary to use an addtional sealer, the first coat of any finish is a sealer, on a few woods,such as cherry,maple & birch pigment stain tends to blotch and a wash coat of shellac is useful there. If you don't want to add any color use super,or ultra blonde.If you like golden oak stain on oak,substitute orange shellac,its cheaper and dries in about a half hour.
Regards
Jerry