What bad guy was threatened to be skinned and have his skin hung on a church steeple?

Hint: Not in Middle Earth.

Farmer Giles threatened to do this to Chrysophylax.

Correct

What was Tar-Herunúmen's crime?

He took the Sceptre of Númenor under an adunaic name.

Yes he did.

Who was the bad guy that invaded the Shire?

Saruman?

Before that.

um...wormtoung? (spelled it wrong!)

Nope.

uh...orcs?

And the leader of them...?

Ugluk? Hint?

Not Ugluk. HINT: Think sports. ;)

Ufthak? I have no clue!

Well, it's hard to give hints that don't give it away...but another hint would be Bullroarer.

I got it! It's Golfimbul!

That's him. :)

Who was the bad guy who, for a short time, captured Frodo with many arms?

The Watcher of the Water?

It most certainly is!

Who was the only bad guy to survive the internal battle in the Tower of Cirith Ungol?

Shagrat

Correct. :)

Whose "thirty white horses that stand on a pink hill" were used as jewelry?

Scathas?

Of course...:D

Who were the two last bad guys to be killed in the tower of Cirith Ungol?

Snaga and Gorbag?

Yup. Your turn. :)

Who were the Gaurwaith?

The wolfmen, the outlaw band which Turin joined for a time.

Right you are!

What was King Folca of Rohan's bane?

That would be the Boar of Everholt.

That would be correct!

Name the bad guy whose name means 'rushing jaws'.

Ancalagon.

Correct, go ahead. :)