Variance Account Questions

Our finance person has started looking into the variance account and come to me with quite a few questions.  I'm not a finance person so I'm hoping someone might be able to help out.  

We've run the WIP rec report on our variance gl account.  I've seen some instances where an entry was made because we missed putting in a cost for a part.  I've also seen an entry for where we didn't put a price in the PO.  In both of these instances there was only one entry for that part and it was a ADJ-CST.  I also have a part where there are 2 entry's that balance each other out, again both ADJ-CST.  I can't seem to figure out the steps in test to make a part post 2 entry's that balance out.  What would create this situation?  If they are truly balancing each other out, why would they even be in the variance account?  

There is a posted column in the WIP rec report.  We run the Capture WIP/COS process on the first of every month.  Post to GL, Post COS/Variance, Capture outdated trans are all checked and the outdated trans date is set to Jan. 1st of this year.  Even after running this, I still see some transactions in the WIP rec report that say they are unposted for this year.  Why would this be?