I want to make an 4 by 3 wall of maps placed inside item frames, and want the maps to line up, I read the wiki and it said that the center of the map is where I first read it (held it and pressed RMB.) but where I was when I did that is not close to the center of the map, it's in the bottom right corner, about 1/5 in from the side.
I understand that the maps now uses a kind of grid system of 8 by 8 chunks (is that correct??), so all I have to do to get a map of the next 8x8 chunks is to walk outside of the current map an create a new one?
The normal mapsize is 128x128 blocks in size, so yes, every map is 8x8 chunks.
All the maps are aligned to a grid. Simply walk outside the range of the first map, and create a new one. It will create a map that is directly next to the other one. When you create the map, you could be located any where within the 8x8 chunks, but it would still make the same map.