Well, it was a ribbon cable that wasn't seated just right. My touchpad is working again, and I can get back into the bios to reset the quirky settings in the Dell Bios. For some reason, ANY hardware change, even something as minor as the keyboard, triggers the Bios to reset itself to default settings (except it DIDN'T remove my Admin password). And for some reason, that reset includes setting the SATA mode to RAID, and setting the boot mode so legacy ROMs are enabled, but I think it left UEFI enabled, but I won't swear it, because I wasn't trying to study the Dell bios, just get it back working.  Word to the wise, here...because of this automatic changes to bios triggered by minor hardware changes, TURN OFF FAST BOOT before you change any hardware out.  For anyone stumbling into this thread with touchpad problems, the ribbon cable for the touchpad is the one above and just slightly to the right of the end of the mouse button switches. Bright sunlight made it much easier to re-seat! And I do have the lighted keyboard I wanted to swap in working .  Appreciate you guys! RESOLVED.  
I dismantled my E6430 to try and upgrade the keyboard with a lighted one. I also removed the handrest and cleaned the touchpad mouse buttons with isopropyl alcohol, which required disconnecting the ribbon cables under the keypad.  When I put it all back, it won't boot as the BIOS decided to switch my hard drive from AHCI to RAID, and my Touchpad isn't working so I can't click on any mouse buttons to change things because I can't move the cursor over to enter my admin password. The lighted keyboard works fine, FWIW. I tried switching back the keyboards, but still no way to move the cursor with the Touchpad or the little "pencil eraser" gizmo.  Hope someone has some suggestions. I can't get into safe mode to help windows find the AHCI driver, because I can't click on the "Advanced options" button without the Touchpad to allow me to click on the button. I've tried to reseat the ribbon cables under the keyboard, but not the one coming from the pushbuttons under the Touchpad because that means removing the handrest again, and I would like some ideas about which ribbon cable does what before I do that again. For all I know, it may not even be hardware causing the frozen pointer. The problem may be a bios snafu or something entirely software for all I know. A little knowledge would be most appreciated. Thanks for any suggestions you may have. I'm going to sleep on it and try again tomorrow because I'm out of ideas 
Touchpad on E6430 not working - ribbon cable? bios gone wild? software?