The Bold Text options affects all the system fonts. That's why the iPad reboots. It's not a huge difference, but it's there.
Larger Text is limited to some of the native apps. It won't affect anything on the Home Screen or slide out panels, or status bar.
The best I've been able to figure out so far for Increase Contrast is that it affect the Notification and Control Panels. They will go opaque (or nearly so) with the option turned on. Doesn't seem to affect transparency anywhere else. At least no where that I've checked to date.