Obfuscate e-mail addresses to deter e-mail harvesting spammers, while retaining the appearance and functionality of hyperlinks.
Of course nothing is guaranteed. By its very definition, "obfuscate" means "to make obscure or unclear", and that's all it's really doing. It's some degree of basic protection, which is better than nothing. Much as how locks in real-life at best provide some measure of deterrent for a would-be criminal rather than absolute security from a determined and capable individual. That said, some testing (as described elsewhere in this documentation) indicates using one or more of the supplied techniques are extremely effective.
Nothing short of not actually displaying e-mail addresses can guarantee that e-mail addresses can't get harvested. Some methods are more aggressive and therefore have compatibility and/or usability issues. This plugin can be very compatible and usable by all visitors to your site, but also has allowances for greater protection with minimal impact (though how minimal is for you to judge).
No. This makes this plugin's implementation of obfuscation more compatible and usable by more visitors. This may leave out techniques that some could argue are aggressively protective, but I feel (based on the aforementioned study and personal experience) that the included techniques are just as effective.
Yes, all techniques can be activated at once (and multiple ones are by default).
No. The plugin filters post content on-the-fly. E-mails will remain unchanged in the database.
The web browser's inspector tool will process certain techniques (such as HTML hexadecimal substitution) before showing the source in the inspector. You should "View Source" to see the raw markup sent to the browser.