What upgrades are possible for a 2000 MBZ S500?

I would like to add/replace a few things on my car and i just don't know what can be upgraded and what can't be upgraded. I want a new steering wheel with wood grain trim, distronic/parktronic. Would these upgrades be possible? Also, the upgrade that I figured would be impossible would be a updated NAVI system ('04-'06 style) is is truly impossible to upgrade the command center. Thanks