While our county has been under quarantine for the last few years,
this is the first year I have actually found egg masses on my
trees. What can I expect in the future?

It will vary from year to year.

Will my trees die?

If they are otherwise stressed or the gypsy moths are really bad, they
can. But in general, they will probably recover from it even if
defoliated.

I read that kerosene sprayed on an egg mass will kill it, is this
advisable?

Not familiar with that remedy but I would think that if you have the
time to seek out individual egg masses you could remove them by hand
(or stick, or ladder, or....). That's what I did on my (young, about
2 meter tall) Apple tree this spring. Some of its leaves got munched
but nowhere near a complete defoliation (mostly not due to my efforts,
mostly just due to not having as many caterpillars as in, say, the
park down the street. This was said to be a bad year).

To make things worse, they found the emerald Ash Borer 2 counties
over, so I guess their next.

Here in PG County, Maryland, they have been on the hunt for those.
They're hoping they can nip it in the bud (by cutting down ash trees
near the infected ones, and such measures):
http://www.gazette.net/stories/11220...03_31978.shtml