Site Accessibility Testing Methods and Best Practices

I've done my best to make my site accessible using the WCAG guidelines and some validation tools such as axe, achecker.ca but I feel like I'm lost in a sea of thousands of 'suggestions' but few hard and fast rules to follow to guarantee the widest reach possible.

I don't really know anybody using accessible browsers so it is hard to get real-world knowledge. What is the most popular browesr at this point - is it a full on browser or just a plugin for FireFox (or Chrome). Do they react different between Windows and Mac?

Are there any mobile accessibility options? What about for iPads/tablets?