Hi all, I'm planning to further my dive into intimacy with my cars by learning INPA and other interesting languages. I'm unsure which cables I will require. I plan on using an older windows laptop with a serial port connection as well as USB inputs.
I have a 98 e38 740i (build date 11/97) and an 05 e83 x3 3.o
Do I need a 20 pin connector with serial port output for under the hood of the e38 and an obd port to USB cable with some sort of chip and pin 7 and 8 connected for the e83?
Will there be times when I would connect the e38 to the computer through the obd in the dash? Will the cable used for the e83 work for the e38 as well?
And finally, recommended sellers, things to look for or things to be wary of?

Looking forward to a new adventure.
Thanks,
Robert