Deployment best practices

We're about to overhaul and rebuild our SCCM. We're currently on SCCM 2012 R2 but have been experiencing a lot of issues with  it and have decided to start from scratch. Fortunately we're a small organisation of around 600 people in a single site location. 

I'm looking for advice and recommendation for the deployment in this size/scenario using the latest SCCM version. What would you advise? Single server? Seperate Database? Seperate WSUS? 

We don't intend to manage servers (ie. we don't plan on purchasing the Server ML's) - does would the impact of this be - given that the only thing we use it for is to deploy patches and are considering whether it would be easier if we deployed patches simply using WSUS instead.

Any advice, guidance and pointers much appreciated.

cheers!