Smarty wrote, on Sat, 13 Dec 2014 11:09:46 -0500:

Generac sells a service kit for each generator including spark plug, oil
filter, and air filter. Just buy it and save yourself (and everybody
else) a lot of confusion.

I didn't know about that, and, certainly Generac support didn't
volunteer that information, particularly when I asked about the oil
and the plug.

But, at this point, I think I'm fine:
a) The oil filter appears to be correct,
b) The spark plug will be compared to the old one
c) The oil is just plain old motor oil (SAE & API notwithstanding)
d) The air filter appears to be a serviceable filter (cleanable)

I'll snap pictures, hopefully later today, as it's not currently raining.