Forget google! Search here!
https://forum.ih8mud.com/electronic-toys/204526-product-review-cb-am-fm-antenna-splitter-firestik-ar-1a-match-maker.html
I don't have any experience with it, but would imagine it would do what you want it to.
EDIT: can't read... guess you got this far. Never...
As for a mic extension, made mine. Bought a length of 6-pin phone cord and a box. Ran the wires, cut to length ,and wired in the box (cant follow the color coding on the package, need to check the orientation on the mic and line them all up). No problems and I'm getting good signal reports...