make a text board t ofunction as a TP

I would like to make a text board; this is the first time I make it.

What size should it be when making it in Photoshop? I mean how many characters on a line?
Can the size of the board be changed after I put the texture on it in case letters drop off?

Maybe silly questions, but I thought to ask them before I have to upload several times for nothing.

Thanks for any info!!

for single characters in a grid ive been using 10 letters in 1 row, you end up wasting abit of space but it makes the math simpler and the script abit smaller but you can really use any grid arrangement you wish to figure out an equation to

and yea the prims can be any size the textures will behave according to your math texture settings are independent of prim sizes (unless you start resizing with stretch textures checked)