I am currently using an addon to serve the value of a .txt file to two different text objects, which works great. I want to force all characters to capital though, and am unsure about how I would do that given the current data flow. I am open to using a completely different addon/script to do this, sadly google didn't turn up any results.
In your script after you have created your text object and are in edit mode for it just run these two commands.
That will convert all the characters in that text object to upper case, but leave it all selected.
If you want to have your text unselected (still in edit mode) run this command after the two above
Documentation on the font operators.
Here is an example script that uses the operators above to get a string from an external text file, convert it to all upper case, and make a new text object in.
This script gets a string from an external text file, converts it to all upper case, and makes a new text object in blender; same as the script above, however this one does not use
No, I don't think there currently is a way to do that, at least without some coding involved, as far as I know.
Closest thing you can do is either use the option "Small Caps" and set it's size to 1, that will make non capital letters look like capital ones though the inserted text is still non caps, or you could find and all-caps font.