(1) You can change the configuration of the CKEditor toolbar in the 'showkase/admin/settings/ckeditorconfig.js' file.
If you'd like to use the 'Full' toolbar, change line 32 from:
config.toolbar = 'Showkase';... to:
config.toolbar = 'Full';Otherwise, you can configure a custom toolbar by changing one of the templates in the file ('Showkase', 'Basic', 'Full') and making sure that line 32 selects the template you wish to use.
Showkase incorporates CKEditor v4.5.7 so please refer to the documentation here: http://docs.ckeditor.com/#!/guide/dev_toolbar
Also, please note that the line number above refers to the current version of Showkase (v1.6.1).
(2) The Showkase Library was designed to accept images only (files with extensions jpg, jpeg, gif and png).
All Library and upload functionality is based around images. When selecting the 'Library -> Images' tab or clicking a 'Browse Library' button, only images are displayed. It would probably take quite a lot of modification to several source files to allow other files types to be accepted by the upload module and for functionality to not be broken anywhere in the interface. Care would need to be taken to filter out non images for Library selections (such as the theme 'Logo') as the file may end up as a 'src' attribute in an <img> tag.
If you need to incorporate a pdf file in your site, the best thing to do would be to upload it to your web server manually and add your HTML code as necessary in the editor (as you are currently doing).
I hope this helps to clarify things for you.