How do I take eBay up a notch?

I have two eBay stores that are selling products in the game niche. I've been doing this for a while, but the products I have are in limited supply based on how quickly I can process and pack orders.

I am looking to streamline my eBay operations and find additional products to expand my offerings. What I like to know:

1) What plugins and apps can help automate or streamline the whole eBay process?

2) What options do I have for finding other products with good margins? How do I get started with reliable dropshipping or sourcing interesting products that can be added to my offerings?

Thanks