I don't think restructuring the profile page is a huge job, it's mostly re-shuffling the HTML output. But hey, you're the boss
Regarding which options to include, here's my vote:
[] Show smilies as icons
[] Show images in posts
[] Show avatars.
[] Show user signatures
. . . . [] Show images in signatures
So there's 4 options with one "sub-option". I really thnk there should be the capability to turn signatures off entirely. If that option is included, "Show images in signatures" is dependent on whether or not it is set. You could disable "Show images in signatures" with javascript unless "Show user signatures" is set.
Removed:
[] Open links in new window.
Modern browsers like Mozilla and Opera are all about placing more control of the browsing experience into the hands of users. With respect to opening new windows, these browsers provide several techniques for doing so (context menu, shift- or control-click, etc.) I'd suggest removing this option (and setting links to open in the same window in the PHP code). That lets the user control the opening of new windows on a per-click basis using their browser's capabilities.