If you are looking for a nice PHP Editor while Hacking WordPress, checkout Eclipse PDT, it does save me a lot of time. CTRL+Click (or F3) on a Function-Name will directly go inside the source (the Definition) of that function, use ALT+Back/Forward like in the Internet-Browser to 'surf' while you hack. This often is more usefull then reading outdated Codex API Infos (The source is naturally more actual then the documentation). Thankfully, WordPress Sourcecode is now documented with PHPDoc-Style Comments as well). With the Eclipse SVN integration called Subeclipse, you can flawlessly get the latest bleeding code, and define SVN externals for (your) plugins and themes. This makes Hacking as well as testing much more easy and is a Free and Open Source Software based Solution. Feel Free, Hack Free, and Blog Free.
Get registered Filter Information:
<?php var_dump($GLOBALS['wp_filter']['the_filter']); ?>
Delete all feed caches:
DELETE FROM `wp_options` WHERE `option_name` LIKE ('_transient%_feed_%')
You can pretty anywhere host WordPress, but as usual some hosts are more compatible then others especially when it comes to automatic upgrades. Here is a little list of WordPress enabled Hosters that I ran over and was able to check.