HOM question

will using more than one character to fill HOM still count as full HOM and get me all the bonus items?

Yep. It's account wide. There is a direct carryover reward for God Walking Amongst Mere Mortals though, so if you want that title you should consider having a "main."

Otherwise, there's no reason you can't fill it a little bit with each character. I used this to great effect on the armor statue, and I think most others probably did too .

what do you get if u get GWAMM?

You will get to display it in gw2.

Many of the "Legendary" titles, such as Legendary Guardian, Legendary Vanquisher, and Legendary Cartographer, are based on having one character with all the contributing titles in each track.

For example, if one character earns all three Vanquisher titles (Tyria, Cantha, and Elona), then he becomes Legendary Vanquisher and gets a fourth statue. But, if "Joe Warrior" vanquishes Tyria, "Joe Sin" vanquishes Cantha, and "Joe Derv" vanquishes Elona, the titles will not combine to give you Legendary Vanquisher. All three individual statues will count towards your overall HoM points, but you will not get the fourth statue.

So, if you want extra points from these title tracks, then it is best to do all the titles in each track on one character.

Note that beyond 30 points in the HoM you don't get anything except titles to display in GW2.