Two other things to mention.

1. There is a HUGE amount of information in the wiki. (link at the top of the page). If you're asking these questions, I would really encourage you to read more in the wiki. There's great stuff in there.

2. The tumb nail test should only be used to test a razor in the early stages of honing to check for micro chips in the bevel. Performing the TNT with a hones razor is not only very dangerous, but will probably do enough damage to the edge that it needs to be honed again. Razors are meant for shaving hair, not slicing thumbnails. YMMV