Music Pack 3 link is not working, which seems to be related to Celtic 3 since they give the same problem (They both link to stuff on Mediafire)
The other ones are downloadable easily enough. Looking forward to playing this mod!
Not sure why you're having issues with downloading. I checked to see if I could download it myself (and not using my mediafire account, of course, to try to reproduce the situation as accurately as possible) and I was able to. Only suggestion I'll have is to wait a while (maybe a day, since the music isn't that essential?) and see if you can download it again.
Well, I only use the Events, so it is kind of annoying... Can't I delete a file somewhere, to get it back to normal?
I forgot I left that in there for some reason. I think it was when I was trying to start giving most of VIET's decisions icons but stopped partway through because I didn't have enough time and effort to do it. They've been removed in my local version.
Anyhow you can just go to "VIET Assets/gfx/interface" and delete all the files in there, that should fix it.
Which face packs do VIET Immersion requires? I have Mongol Face Pack, African Portraits and Mediterranean Portraits, but I still get some European rulers to be black spaces.
No face packs are required, though having all of them are recommended. If you do not have ALL of the portrait DLCs, you should apply the portrait fix (located in the customization options folder; further instructions are there), which is for any users who, well, don't have all the portrait DLCs.
Earning piety to declare war is very hard as an orthodox ruler. Any tips ?
Nothing really short of the typical stuff you'd do in vanilla to get more piety (i.e. piety-increasing traits, hold a bunch of fairs/feasts/hunts and hope you get the piety events, etc.). My related suggestion though is that wars tend to be a bit rarer and more spaced out in VIET due to the increased costs, so plan carefully ahead as to what wars you can and can't declare.
Anyhow, if you're finding it too frustrating trying to get enough piety, I can point you to the parts of the code where you can edit the base piety costs for war.
(On the other hand, this does remind me that I need to throw in a little more for the Orthodox folks someday.)