Is this a bottle of Jameson whiskey?

No. It is an empty 30 oz tumbler with the Jameson logo printed on it. The whiskey is not included.

Will it keep ice from melting all day?

Double-wall steel tumblers this size usually hold ice for many hours, though not a full day in a hot car. Pre-chilling with cold water helps.

The tapered base of most 30 oz tumblers fits standard car cup holders. Check the base width if your holder is narrow.

Hand washing is safer for the printed logo and the finish. Many sellers advise against dishwasher use for decorated tumblers.

That depends on the seller. Many 30 oz tumblers ship with a sliding lid, and some include a straw. Confirm the contents before ordering.

At Etsy, for $20.00, as of our latest check.

$20.00at EtsyChecked Nov 11

Prices are checked against each store and labelled with when.

It checks today's price at every store, compares the alternatives and answers in about a minute.