what is easiest way to change heater core

It depends kind of on what vehicle - but on most cars you're going to end up removing the glovebox, and looking straight back at the firewall. You can work through that opening, and also pull the bottom panels on the dash and work up through there at it.

Your 95 should be the same as my 93, I think. Remove the center console completely. The heater duct directly below the stereo (but on the floor) then needs to be removed. It will be about 7 screws or so and you may need to do a little bit of prying to get the damper out. The heater core will then be exposed. Jack up the car, remove the hoses from underneath the car and you're golden.