You would probably have better luck with this question in the buying and selling a home forum. Additionally if you do a search asking the question, I believe it's been answered several times.

Answered maybe 6000 times.

http://www.gardenweb.com/gardenweb/query/Construction-land-loan

Yes, usually, if you own the land outright, but it depends on the lending institution.

You actually don't even need to own the land outright. Equity is equity in any form.

ETA: If you still owe money on the land the bank will pay that off to roll that loan into the construction loan. My father actually got a construction loan on a purchase option, so he used the equity in property he didn't even own.

Normally, yes.