Nice set of queries. Something similar to this will be in 6.5 that is in the early stages of development along with repair options.
As for trying to track down the problem with #7 and #8. On import are you setting B_Approved to 'yes' on all imported posts? The Bo_Total and Bo_Threads fields in the w3t_Boards table should only match the total # of threads/posts that have the B_Approved field set to 'yes'. If any threads/posts do not have that field set properly you may find some inconsistencies.