Sounds like bad flash to me. I wipe everything including dalvic, cache, system and Factory/data. I restore apps only with no data on these builds. Some have gotten away with dirty flash but most have problems so I don't recommend it.
Our wallpaper will be released when theme is released. It is our signature and original. Wallpapers can be added to the app but it takes photo editing and at least XML skills. May even take smali skills. Haven't dug that far into it yet. That is one of our next projects.
I am familiar with XML but never heard of smali. It's unfortunate because changing the lockscreen wallpaper from the Samsung wallpaper app actually works. So if I could get one in there it would fix it.
But I think it's just the porting of the gallery apps in this ROM that might be hit or miss. When the prompt appears for which app I want to use they both are showing their package names rather than "Gallery". They show up as Gallery in the app drawer, it's only in the default program prompt that they don't.