Thanks for using NextGEN Gallery Optimizer!
It sounds like the trouble you were experiencing may have been caused by wrapping your NextGEN shortcode in [one_half] [/one_half]...
Unlike a standalone shortcode which is detected immediately, a nested shortcode must load using the do_shortcode() function in WordPress, which loads much later. This is okay for NextGEN to insert your thumbnails in the HTML, but unfortunately it's too late for Optimizer to insert the necessary scripts in the header of the page (where they need to load to function correctly). The missing NextGEN stylesheet explains why your gallery images were presented in a single column.
My suggestion would be to use your own css styling to float your gallery to the left (and with greater precision), instead of relying on theme shortcodes which will break if you switch your theme in the future. I could certainly help you customize this...just let me know. Are you using the Broadscope theme, at all? (it's not clear from your source).
To mass-tag all your photos in a single gallery in NextGEN, simply go to Gallery --> Manage Gallery --> your_gallery_name, click the select all checkbox (next to the ID column name), and using the "Bulk actions" dropdown menu, select "Add tags" and click the "Apply" button. You can then enter your tags in the pop-up lightbox window, and they'll be applied to every selected image.
Hope this helps!