Questions before considering/buying the Precision 7875

I got a few questions before considering/buying the Dell Precision 7875:

I'm considering buying this workstation with AMD Ryzen Threadripper PRO 7955WX (64 MB cache, 16 cores, 32 threads, 4,5GHz to 5,3GHz, 350 W).

I'm looking for a professional, reliable, stable system for general computing, gaming, video encoding.

Questions:

1. I don't need an expensive Quadro graphics card as I will not run professional 3D applications. When I order the system without a graphics card, does it come with all the cables to install a GeForce RTX 4080/4070 consumer graphics card?
2. I want to add a blu-ray burner. Dell does not offer one for this system. Does the workstation come with the cables to install a 9.5mm slimline blu-ray burner?
3. Does the system come with m.2 and 2.5" SATA drive expansion bays/slots so I can add my own storage? Or does it only comes with the bays for the drives I purchase with the system?
4. The Dell memory upgrades seem overly expensive in the configurator. Can I just buy the minimum RAM config and buy my memory modules from the Crucial configurator instead? Or will that lead to compatibility problems? https://eu.crucial.com/compatible-upgrade-for/dell/precision-7875-tower

Q: Why don't you buy a gaming PC?
A: Because I prefer a reliable system, that does not look like a toy and comes with onsite warranty.