Hi Outatime,
No sweat. We aren't formal here. There are couple great tools out there for converting your files so I think you are going to get what you want.
The first tool is Libprs500. You can get it at:
https://libprs500.kovidgoyal.net
It will convert your rtf, txt and HTML files to LRF (Sony Reader format). It does a lot of other stuff too. If you have windows, the author has written a nice windows GUI, so get that. You can also view your converted docs on this GUI to make sure the type is big enough (leave the screen size alone).
The next tool is PDFLRFwin-0.99. It can be downloaded here:
https://www.mobileread.com/forums/showthread.php?t=13135
Use it on PDF files. It will turn a page sideways, remove margins and thicken the letters to make them more readable. Use the default settings.
Whether you will like what you see depends on the original document and how you process it. A normal 8.5" x 11" page needs to be rotated sideways and have its margins removed in order for the type to be read comfortably. A 40 column document (pocketbook paperback) does not need to be rotated, but you still will want to remove the margins.
I don't have an answer for you on Word docs. Maybe someone else here can help.
Good luck,
Mike