Does it keep drinks hot and cold?

Yes. Igloo lists double-wall vacuum insulation with a copper lining for both hot and cold retention. That is the same insulation approach used in its standard stainless cans.

Is the lid leakproof?

Igloo calls the threaded lid leakproof and removable. The sliding mouth tab clicks into place, but a sliding tab is not the same as a sealed screw cap, so carry it upright in a bag.

Can it go in the dishwasher?

Igloo does not state dishwasher safety for this can. The matte 3D print is the fragile part, so hand washing protects the design.

It holds 16 oz, the standard can size in Igloo's lineup. That fits a large coffee or a full can of soda with ice.

Does the rubber base come off?

The rubber coaster is built into the bottom. It is not listed as removable, so treat it as a fixed part of the base.

Is it good for a Snoopy fan?

Yes. The matte 3D print of dancing Snoopy and Charlie Brown is the main draw, and the stainless insulation makes it usable daily rather than just decorative.