I'm planning a paint job on my silver 240.

Keeping the metallic silver and considering subtle metallic charcoal for hood stripes and same on lower panel below doors.

I know virtually nothing about modern paint technology. Want a good, high gloss and good chip resistance.

Also, is one type of paint easier for stone chip touch-ups?

A base coat/clear coat paint job with a catalyzed acrylic urethane clear coat will provide a pretty strong finish. It could still chip, though. And bc/cc is harder to touch up if the chip penetrates through to the primer or metal. A single stage paint would be easier to touch up (no clear coat).

I'd recommend finding a good paint/body shop and talk to someone there to see what they recommend. Avoid a commercial shop that does nothing but insurance work, look for a shop that specializes in restoration and custom work.