Pretty much no. The extension uninstalls all its observers when the blockage mode is off and hence it has the minimum possible impact on your browsing experience.
Is it possible to change the location of the toolbar button as I am not frequently using the extension?
Yes, read a Comprehensive Guide to Firefox Customization to find out how to change the toolbar button's position. If you are not using the extension too much, you can also try my the other extension to completely disabling this one when it is not neccessary, Add-on Manager with Profiler. Basically you can create multiple profiles and enable and disable certain extensions within a profile.
The extension icon is not appearing in the incognito mode in Chrome and Opera browsers. Is this an expected behavior?
Well, in Chrome based browsers, extensions are not allowed in the incognito mode by default. Open "chrome://extensions/" and check "Allow in incognito" and you will notice the icon appearance in the private windows. Also blockage will automatically applies to the private mode as soon as the icon is present.
For Firefox version, white-listing is not available unless you are on the WebExtension version of this add-on.
In Firefox browser, there is a flag called
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I would recommend this add-on to everyone, especially people who are looking for an easier way to have control over websites.