Well, believe it or not, I finished the job and it came out pretty good.

The worst of it all was cleaning the old tile so I could re-use them. These are not tile easily found in Home Depot, so I had no choice. Cleaning the tile took me an entire weekend of scraping. To clean the tile I let them soak in muratic acid and then used paint scrapers and steel wool to remove the old grout and thinset. Maybe someone else has a better idea but this worked for me.

Here are a few things I learned in the process:

1. Take pictures of the original installation so you have a guide.
2. After removing the tile and old thinset, fill any cracks in the concrete by grinding them out and filling them with hydraulic cement.
3. When applying the tiles, follow the old tile lines, don’t try to plumb it up since the previous installation may not have been plumb.
4. Don’t apply thinset on hot sunny days, it will dry up too quickly and you will end up scraping it off again.
5. During the application, make sure you follow the previous pattern! I have a row of alternating tile patterns. I missed it when I started and had to remove about 50 tiles and start over (I was not happy).
6. If you have small tiles, remember that now you have no backing you will be replacing the tiles one-by-one (not in sheets like they were installed originally) so the installation will go very slow.
7. Buy some cheap tarps to cover your work to keep it dry.
8. Clean up any thinset or grout drops quickly.

Thanks for the tips from everyone!
Frank