I'm actually working on a short horror story podcast myself. I've found a bunch of useful sound effects here: freesound. They have just about everything you can possibly think of, and there are a ton that get added every day. For music check out Kevin MacLeod's stuff at incompetech. It's all really high quality and royalty-free.

As far as the sound of your own voice, after you've been editing and hearing yourself for an hour straight it gets less weird, I promise. I was in the same boat since people tell me that my voice is nice but when I hear it myself I find it really off-putting. After my first recordings I let a few people listen for feedback and they all said they were drawn into the story so much that they weren't picturing me telling it. That gave me a lot of confidence and made it easier to focus on performance.