Yes latest version 2.87. 3.4d beta AB.
Maybe it is a bug being generated with the beta AB then.
Let me download the release version of AB and try to replicate.

UPDATE

I reloaded the current release version of AB (3.4c #378) and cannot get these bugs to occur. When trying to load the roster I created with the BETA AB I get these error messages.

http://i85.photobucket.com/albums/k6...ps9c1914e1.jpg

http://i85.photobucket.com/albums/k6...psbdd38fe7.jpg

So I am pretty sure this was a BETA issue.
On a side note is there a way to have the current release of AB and the Beta installed at the same time? One just overwrites the other.

Skink Cohort Brave
 

Whenever I upgrade a skink cohort into a brave it adds 12 points to the army and unit's point total, but I believe it should only be 10 points. Am I wrong, or is this an error in the file?

I just tried, and it's adding 10 point to the unit value (the brave is 15 as it should be) and again +12/17pts for the lone brave when poisoned attacks is selected. So, sorry but it seems I cannot replicate the bug you're having. Could you please provide a screenshot?

Cohort Brave
 

It works correctly for the first cohort unit, but the second cohort unit has the bug I describe above.

Thanks for the image let me go bug hunting now.

Upon further review, it is applying poison to the brave only. I built a roster and saved it (brave applied correctly). Then opened another file, then went back to original file (all in the same session) and it had applied the poison to only the 2nd (of 2) cohort unit with a brave when I reopened the file.

Fixed for 2.90 release which is now available.