Is the top solid walnut or veneer?

Both are used. The top is American black walnut, and the construction combines walnut solids with walnut veneers over the carcass, which is normal for large panels that would otherwise be unstable in solid form.

How big is it compared with a typical cocktail table?

It is 54 inches wide, 30 inches deep and 18.5 inches high. That is wider and deeper than many standard cocktail tables, so measure your seating gap before buying.

Does it have storage?

Yes, but only open storage. There is an open space at the back with custom metal pulls and a back plate, with no drawers or closed compartments.

Will it sit flat on a rug or uneven floor?

It has adjustable levelers on the base, so you can correct wobble after placing it on carpet or a floor that is not perfectly level.

How should I care for the Dark Roast walnut finish?

Keep it out of direct sun and away from heat and standing moisture. Dust with a soft cloth and use coasters; avoid silicone polishes and household cleaners on the finish.

Does it need assembly?

It is a base-and-top table with tapered posts and levelers. Expect at least minor setup to attach or level the base, and keep the hardware with the table if you move it.