Re: buttons.. stickum and orientation update
Rum
Just wanted to update and say that I haven't been ignoring your great advice, quite the contrary but wanted to pop back in just to update and thank you all again for the great ideas and advice.
I haven't tried Tom's interesting suggestion of tape on glue yet.. that certainly bears more investigating - also while reading up around that idea I found David Reed Smiths interesting article on using that idea for bowl reversing: http://www.davidreedsmith.com/Articles/BlueBowlReversing/blue_bowl_reversing.htm
The hot melt still seems slow when gluing one or two buttons at a time. So far I've thought of two possible ways to speed that up, first would be to keep a puddle of melted glue on a little hot plate for quick use. The other is to pre-turn a bunch of glue blocks/mandrels and batch the process (possibly combining the hot melt+tape method), which may in the end be the best choice. More experimentation in progress.
I do have a couple of possible alternative tape choices on order, the local selection was poor and spongy. Watching Tom's excellent video it was apparent the stuff I'm using and others I can find local is definitely not as robust.
I'm somewhat happy to report that I got up to about 5 per hour with 100% success using the tape method, still not very efficient but its not quite as bad as it was before either and the percent of time spent turning is definitely higher. This was with using the same tape I'd been using but with a few changes.
First I gave up on reusing this tape, better tape with more stickum is most likely a different ball of wax. The failure rate with reusing this tape approached 1 so it seemed better to cut my losses and just put fresh on each time.
Second I moved to putting the tape onto the button first. This is contrary to Doc's suggestion, but observing my failure modes it was always the button coming off of the tape, not the tape popping off of the mandrel so it seemed that getting the best/cleanest contact at the highest failure point would be the the "best". If I could re-use the tape that would certainly be different, so will revisit this later with the other tape choices.
Finally I sped up by slowing down. The tape seems to really like a bit of contact time to set up so I'd put it the next button on the lathe and go tell the dogs that wood chips aren't potato chips again and scratch their butts or put some BLO on the finished buttons or whatever for a minute or three and that seemed to help set it.
As to Brad's excellent point about grain orientation. I have made quite a number of end grain buttons (mostly of the rustic round cut off of a branch variety, fewer turned ones) and yes they are substantially faster and work/look fantastic for a lot of uses. There are a couple of reasons I decided to go cross grain here. I was a wee bit dubious about the strength of end grain ones of any size and the initial target for these is a "high wear" environment (decorations on a hoddie for my cousins 5yr old daughter). I see you've made end grain ones over 2" so I was apparently being overly cautious. It might not be obvious in the picture but I put the holes carefully at a diagonal to the grain to maximize strength as well. I've also been in a "use up the scraps and smalls" mode and happened to have some pieces of roughly the right size (notably the lilac which is really tough wood) so that was also a consideration.
There is also more than a bit of having tried it wanting to make it work 
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