Just returned a couple weeks ago. You are wise to rent from Alamo. It is right at the airport. ( Check Costco prices, may be cheaper than Alamo direct.) Molokai is a very small island so very easy to drive around. Realistically, you cannot get lost because there are only a very few main roads. Hope you can get the plane ride that stops at Kalaupapa. You will have fabulous views that right now is the only way to see the Kalaupapa area. Depending on whether or not there is a need to stop at Kalaupapa will determine whether the flight will stop there. Kaunakakai is basically the main town. It is the equivalent of a large block. Lots of free parking and several places to eat, and the bakery referenced above -- Kanemitsu Bakery. I'm listing a few stores/restaurants just to give you an idea of how easy it is to get around: Misaki's; Molokai Pizza Cafe; Dave's Ice Cream. Very local ice cream flavors at Dave's.
Viewpoints are the Overlook to Kalaupapa; the Molokai Museum which is on the way to the overlook; and a drive out to Halawa Valley. Based on your timeframe you will probably not be able to drive all the way down to the Valley but drive out that way and enjoy the views, passing St. Damien built churches, and viewing the islands of Maui and Lanai. Molokai is old Hawaii. Beautiful and serene. People are very friendly and sincere. Little shops and places to eat within several of them. Average driving speed -- 35 mph. Very very laid back. Enjoy. Fill up your gas tank before returning to the airport. Kaunakakai is the town to do all eating and gas filling. (Basically, the only town.) I was there for a week, drove every speck of the island and used less than a tank of gas. Reserved a Camry and was given a Jeep Cherokee.