is there any way to merge old hosts. or even existing hosts that have had more than 1 os/hostname? not a big deal but would be nice to see the total combined for my old p3 xeon rather than the 5 entries it has.

Unfortunately, you have to go through to each individual project and merge your hosts. Sadly, you probably won't get them to line up for BOINCstats on an inactive host, since each project will probably delete a different iteration (host CPID). Surest way would be to merge hosts on the projects before letting it run out of work and detaching, so you stand a chance of getting the same host CPID. Don't know for sure, though; maybe someday BOINstats/BAM will have a "Sync retired hosts" feature like it does for projects?