PROBLEM SOLVED! Thank you for all the input and suggestions. The solution which reliably works for me is that the file to print must of course be in gcode, the file name on the SD card must be 8.3 compliant. The SD MUST either be in the printer on power up or inserted for a restart/reboot. Then the file was able to be selected and printed via LCD without anything connected via USB. I guess I had always had the printer on when trying to load the SD and start a print, which never worked... The LCD is now FULLY functional and the printer can be used, tuned, and operated stand alone. A mod I made was to drill a hole in the mainboard cover case (front side) and make a guide for a small plastic tool to be inserted so I can push the reset button in the middle of the mainboard and still have the case installed. Saves me power cycling the whole thing everytime I remove the SD to add a print file etc.
I hope to post a few photos of my setup soon. I finally got the heated bed up, and a few cooling fans, power supply mod, etc. Nothing special but I'm happy. Next is a simple cover to control air movement in the print area. I'm thinking an inverted plastic tub from wallyworld or that container place. Would be able to just put it over the whole thing for the big prints that are more touchy to drafts and will take so long I won't be around to be bothered by the cover.