What kind of noise does the tranny make (rattle, clunk, thud, grind)? It may be a bearing. If you can find a good condition used tranny from a junk yard, it will be less expensive than paying someone to rebuild yours.

You should not have oil in with your spark plugs. This may just be the spark plug gaskets on the valve cover. These are cheap and easy to replace. Hopefully it isn't something else.