About the extre DVD episodes... According to OMNI's blog, The one that is to be included with DVD 4 (on sale September 25th) is going to be “packed with the charms of the characters of sola”. (My chances for getting the hot spring ep just went up
Details about the last extra ep (included with 5th(final) DVD) are unknown. Make of that what you will. Personally, i hope that the last "extra" ep will provide us with "extra" information about the characters - perhaps an ep about the origins of Matsuri's kind or something like that. Perhaps a little side story about our hunter and the rozen-loli.
Either way, i hope they are not going to keep the ending for the last extra ep... i would be spewing fire :S