First off, welcome to the community. There's a lot of info contained here and on the 944 section of the NASA Forums so you've come to the right place.
The first question I have for you is have you done any HPDEs or have any experience other than Auto X? Wheels to wheel racing is a whole different animal than cone dodging and as such, takes a different mindset. If you haven't, I would recommend you start with doing some HPDEs with the car as is. If you've already been AutoXing it, then its likely already decently setup for a DE week end. There are a few groups that run around Texas as DE only, but NASA also incorporates DE classes into most of their race week ends. NASA's DE latter is also the first steps towards earning your racing license. Another good group that I like doing DEs with is The Drivers Edge and depending on where you're located, Texas World Speedways Performance Driving Group. Both will provide an instructor and a safe, controlled environment for you to learn in.
After you get a couple of DEs under your belt, re-evaluate if W2W is where you want to go. If you still have the desire, which all of us Texas guys hope you do, then you need to decide if you want to build or buy you're race car. Everyone's position, desire, time, skills, will power are all different so building or buying is a better or worse decision for each racer. If you decide to build it, there are many build threads on this forum as well as a few helpful articles inside the Technical Articles page of this website. Many guys will build towards a Spec legal car while doing DEs. I chose to buy because it got me racing the fastest and I didn't want to go through the process on my first race car. It can also be cheaper a lot of times to just buy an already established Spec car. There are a few good ones currently available in the For Sale section, and we have a good relationship between the Texas and Rocky Mountain region, which is where more than a few cars here have come from. The Rocky Mountain guys make it a point to build extra cars when able to sell off and improve car count. A lot of times these cars are very reasonably priced, decently sorted and just need a few safety bits to go racing.
Lastly, at the very least, come out to a race the first chance you get. We are in the off season in Texas now due to the heat, so our next race is at Eagles Canyon on October 6-7. They will be doing HPDEs that week end as well. Also, let us know where you're located. That will help us point you in the right direction.