Viewable deck, yes, it's a good idea. I actually did even think about it for the initial release but hit the 13k size limit fairly quickly and couldn't really squeeze it in in favour of some actual content. But yes, now I can (kinda forgot about it and grew accustomed to playing without it myself) and will add it in for the next patch! And seeing them in a correct order might indeed be nice as a relic (I've done this too on some past deckbuilder games of mine).
True, wildcard description is pretty vague. Will find a way to improve these too.
Blanks are kinda intentionally "bad". To do have a purpose with shouldn't be used all willy nilly because they can block you off or do exactly what happened to you. Allowing to place them would have few problems. For one, they wouldn't follow the same rules as other tiles. All other tiles can block paths but must be placed so that they connect and therefore the character will also find a path and move there. Not adding them to deck could work but again, it would be a special behaviour conflicting with how everything else works.