what ever became of Harriet MacGibbon who played Mrs. Dryysdale aand Jerry Scroggins who sang the theme? I checked IMDB.COM, but they're not listed, and I can't find anything about them on the shows other websites.
On the "E! True Hollywood Story", when they ddid the sshow recently, they weren't eveen mentioned.

Here's what I know:

Harriet MacGibbon, was born on October 5, 1905, in Chicago, Illinois. She died on February 8, 1987 of pulmonary & cardiac failure.

That's all I could find.

What a goomer is? In what episode does the term occur?

Granny would sometimes call someone a "goomer". I don't know what it means; it probably means someone who's a little odd or strange.

There is more info found on imdb.com:

http://www.imdb.com/name/nm0532251/?fr=c2l0ZT1kZnxteD0yMHxzZz0xfGxtPTIwMHx0dD1vbnxwbj0wfHE9aGFycmlldCBtYWNnaWJib258aHRtbD0xfG5tPW9u;fc=1;ft=3

http://www.imdb.com/name/nm0778620/?fr=c2l0ZT1kZnxteD0yMHxzZz0xfGxtPTIwMHx0dD1vbnxwbj0wfHE9c2NvZ2dpbnN8aHRtbD0xfG5tPW9u;fc=6;ft=21;fm=1