I agree with Rick and Micheal. Asking which lens or enlarger is quite a bit premature at this stage.

There is a great book by Barbara London and John Upton, titled "Photography". It's quite an expensive book if you buy new but since it is often used as a college textbook for photography courses, old editions are available quite cheap. (I bought mine for 25 cents!) I highly recommend it. It gives you a very good overview of the process with enough details from start to the end.

You might want to find a club or an art school with darkrooms before trying to setup one of your own. Or - depending on where you are, one of APUG member may be able to show you his/hers. If you are in Central Florida, you are welcome to come see mine.

I think it's important to learn the basics first. Many of us here have been doing this for years - in some cases, for decades. We all have tweaked our process to our liking. It may be more confusing for you to try to piece together a working process from many individual processes.

Often, the choice of enlarger starts with what's available in your area. Mine is Omega D2 and DII. I bought one for 40 dollars and the other one was free. I picked up nice Nikkor lens locally and on APUG classified. My suggestion would be to read and investigate local availability first.