multi-thread sophia does support multi-thread access (and sophia's compaction is multi-threaded too).
multi-process sophia does not support access a same repository from different working processes at the moment.
database sophia does support creation of a additional databases (which can have their own directory) run under a
single environment. Any number of databases can be involved in a multi-statement transactions.
append-only sophia does not do random disk access for updates.
Please let me know, if you still have any questions left.