Spawning letter tiles evenly across screen

I have been watching the various Unity 2D tutorials available on Lynda as well as on the Unity website and I am trying to create a test game that simply has a grid of letters that are evenly distributed on the screen (think of a word search).

I have my actual letter tiles that were made in Illustrator (128x128 pixels) that I have imported into the project. I also have a Letter prefab that has a public Sprite property which is going to be set to a random letter in the alphabet (basically it loads the letter tile by selecting a random letter, and then loading "Letter_X.png" where X is the letter it selected).

This is all fine and works great when I manually drag the Letter prefabs onto the screen. My issue is that I am trying to get the game to spawn in a grid (of any size) of letters onto the screen and have them all fit nicely.

I have a general idea of what I think I need to do. I know I need to do the following:

If my grid is 10x10

• Divide the screen width by the number of horizontal tiles in the grid (10). This will give me the size of each "tile"

• Use the result of the above calculation to scale the size of the sprite accordingly.

• Loop through each position, instantiating a Letter prefab at the current "grid position".

I am currently stuck on the third step. If my original sprite is 128x128 and my Pixels to Units is also set to 128, how would I then convert a location on the screen (which is not in units) to a position in the scene that is at the exact same spot. Further more, how would I make sure that my camera can always show all of the tiles on the screen without having any bleed outside of the edges of the screen?