I've been looking at the map called Complete Mobile Grids, and from what I understand, making a grid mobile is making a certain amount of air units, then centering a location on another players air unit, also created with the others.
Does this mean that the range of mobile grids are limited to only being a close difference?
Or would you be able to make enough units to actually change the distance of the action that is using the mobile grid?

You can find the answers to those questions and a good explanation on grid systems in the wiki article: http://www.staredit.net/starcraft/Grid_Systems

However, if you need clarification, feel free to post here (or wait another few minutes and someone will post "Yes" to both of your questions, depending on the context in which they interpret them).

Post has been edited 2 time(s), last time on Jun 24 2012, 11:24 pm by Roy. Reason: Be nice, past-Roy

There's a map in my Tests Compilation that goes through and shows exactly how a grid works, when you play the map.