This not a configuration I would recommend as -

1. The mappings with TAB wont work in terminal.

2. <C-t> mapping is default map for ctags jump back.

And if you are going to be a long term Vim user, better configure Firefox like Vim than Vim like Firefox. I use Pentadectyle extension to get Vim like bindings in FF and I love it.

For switching tabs I use <c-n> and <c-p> for next/previous in command mode. Under insert mode, its default map for autocompletion which again I don't prefer remapping. Since I don't prefer to switch tabs in insert mode, that's ok.