It would be nice if we could customize the dropdown box of "Files of type" when opening new files. I am currently running into the problem of the template files used for two of our major sites use .tpl as an extension, so every time I want to open a file I have to hit the dropdown and goto "All Files", pretty annoying.

It would be nice if we could customize these options ourselves, or at the very least set the default option to use(in my case I'd use All Files as the default).

Why don't you open files through Project manager tree ? or through File Explorer docked window ?
I believe it's much faster.

The file explorer window is much too small for me, I end up having to scroll left and right constantly. This also doesn't help that the files aren't listed in the window if they don't match the file extensions. I work with many non-standard extensions and it becomes a pain to constantly change the dropdown box.

edit list of extensions for one of languagies and use it in the combobox.
List of extension is in the Editor tab of the tools->settings dialog.
Language can be selected in the leftmost top combobox on the same tab.