Well, several months ago my tank focus was on two tanks with a turtle in each. I bought tons of plants and really didn't care about snails and actually wanted the buggers to get in my tanks. My turtles were very, very effective killers. Anyhoo, the snails never took.
Many many people say ya the snails are a terrible thing to have, they get in your filters and blah blah blah...never had a problem.
After I rehomed my turtles though, I opened up my canister filter...there was a full-on snail village in there. They never did any harm, but I killed them. Too bad. I just used hot water and ran it over all the media.
No snails have ever surfaced in my tank again...for better or worse.
Oh ya, the eggs will look like just a little small circular patch on the glass about the size of a pea. It will be very clear and unobvious.