Any place that sells batteries can tell you what size battery to purchase.
Through the drivers wheel well You must remove the driver tire. The batery is behind the wheel well cover closest to the bumper.
In the trunk
I have found that on my 2002 Concorde, I can turn the wheel all the way to the right as in making a right turn. Then you have access to the battery cover in the front wheel well cover to the front of...
It is in the trunk, under the right rear corner of the carpet.