For easy editing of flags you can use those templates for wmo:
viewtopic.php?p=45659#p45659BTW I maded some custom portlas for my model. Sometimes
it works perfect and sometimes it's not. Maybe I record a video about everything I know about wmo's after my exams at university. For you thing about flickering it may be caused by that you just copy portals from blizz model and portal size didn't match to yours entrance.
Also If I remember you made a
vid abot how to make you wmo's to be like transport(I mean that bug when you leave youre transport than you still moved with it) about MCPV chunk. Still don't know how to interpret this info in 3d software so you're welcom to investigate this.
Really didn't know what the hell if convex volume planes.
About MOCV chunk: I making the same things as you before I got export vertex color script to work. But for example I changed some vertex colors to another color manually(check vertex Id in blender and then change the color in 010.
And finally about outdoors and indoors batches in group header: when you set youre group as indoor and didn't set batches as indoor then you group will be visible from outside even without portals. But if you set youre group as indoors and set batches as indoors too then from outdoors you group will be invisible from outdoor until you get into this group. here is a pic(those brushes are used as markers where I get entrance to my wmo group):
[attachment=0:37irorz9]WoWScrnShot_062015_233155.jpg[/attachment:37irorz9]
Also don't forget about changing the flags in MOGI chunk of root wmo. Yours minimap not become full black (if you didn't set the path in file of minimaps(the one that used for adts too)) or didn't change to your indoor minimap(if you set this path) if you didn't change both flags of Root(MOGI chunk) and group(MOHD chunk) wmo files.