How to disable BitTorrent?
Uncheck Enable under BitTorrent.

How do I Identify as Opera, Firefox or Internet Explorer?
Right click → Edit site preferences → Network → Browser Identification [or] CTRL+F12 → Advanced → Content → Manage site preferences → Add → [TYPE] Site → Browser Identification

How can I disable web page thumbnails when hovering tabs?
Uncheck Use Thumbnails in Tab Tooltips.

How to hide / disable Speed Dial?
Set Speed Dial State to 2. This will remove X in the upper right corner.

Press CTRL+T and click Hide Speed Dial button at bottom right corner [or] set Speed Dial State to 3. This will remove Show Speed Dial button in bottom of blank tab.