Installation questions...

I am thinking about switching, kind of tired of having to beg Xfinity for a discount every year. But I have a couple of questions.

I have my own router setup that changing is a complete no go (I have an automatic site to site VPN to my office) can I just get the tech to plug in ethernet to it?

Also can they do the installation in an interior location? I know Xfinity will only install on an exterior wall, so I paid to have coax run to the interior closet that I keep my networking equipment. Does FIOS run the fiber to the interior?