Whatever you get as far as shoes and clothing, get it quickly!

Everyone is unique. For example a pair of shoes and cleats good for one person is not so good for another. Give yourself timwe to locate alternatives.

Plus, things usually get better and more comfortable with a little use... You want to be past the majority of the break in period before you start the ride.

Some mountain shoes will be a little heavy because they'll have big lugs in the soles... just like aggressive knobs on a knobby tire. Good for mountain use, but a compromise would be good for what you are looking to do... Otherwise they will be fine. I use Lake MX-101 which they list as a trekking shoes. they are like their mountain shoes, with a little smaller lugs to cut weight... I use mine with Crank Brothers Candy C pedals and they work for me, and are pretty good to walk in as well.

Get the gear, and take a couple of long rides before the trip to make sure that what you get works well for you.