First off... do whatever works for you. Don't feel like you HAVE to go clipless... because you don't.

You will get more power out of your pedaling... if you go clipless... but maybe you don't care?

As far as the cleats... if you get mountain biking shoes, you can get cleats that will be in the sole of the shoes. So, you can get off and walk around comfortably. There are many options in shoes and pedals.

In the end though, do what works for you. Best of luck!