Ahem, before anyone of you comes to Europe, I think there's something to say about...

> Street Signs

> "Yield" is "Give Way" there. It's "Give Way" in England, too

Usually is a white triangle with a red trim pointing downwards. Everywhere in Europe means "give way". In Italy has the special meaning of "Only loosers give way" (winners usually win a free trip to the local hospital).

> Instead of "Do Not Enter" signs, they have "No Entry" signs.

Round red circle with a white tick horizontal line. In Italy has no other meanings, but if you decide to ignore it the sign won't mind.

> Speed limit signs, they have white circles with red trim and just a number.

That's the same, except that in Italy they're not a 'limit' but a 'suggested speed, but if you're in a hurry, I won't mind'.
We've also mandatory speed, thats a blue circle with numbers in white that indicate the 'minimal required speed' (usually on freeways, highways and extraurban high-traffic state roads).

> Their equivalent of "Slippery When Wet" sign is hilarious.

I've seen some of them. We've both versions: with crossing tracks and with not-crossing tracks. The complement is a rectangular sign with a picture of snow or a grey cloud with rain (or both).

> The sign is a white circle with a thin black border and a thick black diagonal slash through it.

This means "end of all previous limits". End of speed limit has black numbers in it and 'resets' the limit to the default for that particular road (50km/h urban, 90 extraurban, 130 freeways and highways). The sign you saw, in Europe, ends any previous limitation.
In Italy, expecially on highways, the sign is often interpreted as "do what you want, I won't mind".

> From time to time, there were triangular signs that had just an exclamation mark on them.

Generic danger ahead. A complementary rectangular sign (usually in local language, except in Switzerland, where they're in French, German, Italian and Ladin(*) ) will specify what type of danger.
Usually means 'be careful', but in Italy has the special meaning of 'other people should be more careful'.

> The toilets were not American Standard brand. They were "Dux."

Maybe you don't know how hilarious this is for Italians: "Dux" was the title for Benito Mussolini when he was ruling Italy (1922-1943).

Sun.

(*)
about the 3-languages signs in Switzerland, try to ask to Andrea how the Maloia Pass was last summer...