1. It's browser independent. You have to import security certificates for each browser, but this is a step which will eventually be automated (https://github.com/aniketpanjwani/chomper/issues/8).
2. In both Firefox and Chrome, you can enter Private Browsing/Incognito mode, where extensions are automatically disabled, so you'll be able to evade blocks. It doesn't matter if you're in incognito mode while Chomper is running - you'll still get blocked.
3. It's usually trivially easy to disable or uninstall browser extensions. Chomper is marginally more difficult to disable when you have root privileges. However, unlike browser extensions, you have the option of tying your hands so that it is entirely impossible to remove a block (https://github.com/aniketpanjwani/chomper#hardcore-mode).