1. You cant adjust the grid afaik, but you can change the amount the grid, example: 1unit = 1 meter. 1unit = 10 meters. This is mostly used by games as flightsimulator that uses scales. Though at the bottoms are 3 magnet icons with other symbols, toggeling these can turn on snap to grid.
2, this is a viewport set-up, it should be only in the active one, unseless you select all viewports, you can adjust it here:
right click on the perspective word brings up this:
With transparancy you can adjust the blending etc.
3.There is no big deal behind this, let me show you:
In this picture i still had both axis select as default, without editing anything, only going into vertex mode etc.
And here i dragged my mouse over the z axis you see in the object and moved it along that one.
I have searched for the water a long time, now i can guide people to it and offer them a bowl to drink.
@trapt, Shame you dont enter, but would you mind showing uss your work if you finish it? Im always interested to see other people's work.