Depends on the yeast you're using, among other things.
To get a good idea on where to start for the honey amount to use, go here: Got Mead - Mead (honeywine) making, mead drinking, mead recipes - Mead Making Calculator
Keep in mind, 12# of honey is 1 gallon liquid volume. But, don't measure honey by volume. Just use that to offset how much water you'll add to get to your target volume.
For the yeast, I prefer Lalvin strains
which are also preferred by many mazers. Depending on how strong you want to make the mead, and other characteristics, select the yeast that matches. I find a lot of people use (and like) EC-1118 or K1V-1116. D47 is also a good choice if you don't want it to be around 18% ABV.
I would advise reading over the newbee posts on the Got Mead? site too. Learn about feeding, degassing and aerating the must. As well as when to stop.
You CAN make a mead go to 18% (or higher) and still have it come out sweet. It all depends on how you formulate the must, and how you work it. There are more than a few options there.
One thing I would say NOT to do is heat the honey/must above 100-110F... Once you do, you start to lose the more delicate flavors and aromas in the honey. Also, Irish moss has NO place in mead. I know it's in some of the beer making books, but it's not used by any of the mazers I know.
Keep in mind, mead is NOT done at the same speed as beer is. Expect the mead to take several months before it's ready for drinking. If you make something above 14%, plan on a year from mix to glass. Above 18%, plan on about 1-1/2 years, or more. Also, don't rack until it's ready. With the exception of one yeast I've used, I've waited until the batch was fully done with fermentation before even thinking about racking. Even then, I waited for it to settle more first (going a couple of months). With 71B (the exception) you want to get off the lees once fermentation is done.