How to show dot underscore ._ files?
Open up terminal, and write:

defaults write com.apple.finder AppleShowAllFiles YES


This makes you see dot files and hidden files in a grayish tint. You open . files with right click open. I do not know why you cannot just double click them though. If it is a problem, ask a separate question on that.



Just a little bonus:
You can hide files by issuing:

chflags hidden /path/to/file


and unhide by issuing:

chflags nohidden /path/to/file