It was zoned light commercial, but after going through a long process with the county, I was allowed to build on it using a use permit, and keep the light commercial zoning.

Jury will decided in your favor (most likely), but it's a painful process.

We are also in the process of renovating our basement to sent it out.

I know I have to give the tenants 60-days notice to vacate but if they do not leave do I have to go through a costly court process?  

I would love to get to know the flipping side of the business and I would be more than willing to help out any active investors in any way I can during my off time from work so I can familiarize myself with the business/processes of flipping houses.

Aside from predicting the future, how can I change my process so that these letters come in a more timely fashion?

It is better for them to get half the profits than no profits, and you gain invaluable experience as they take you through the process with them.DO NOT go half-cocked and mail without having an understanding of the legal requirements for your area for assignment contracts.

Let me know if you have any questions about the process!

You are going to learn more by implementing the process than anything else.The most important thing is understanding timing of a wholesaling transaction and writing the contract correctly.

How far along we're you in the process ?