Which Processor to Buy? Reality Check Needed.

Not replaceable. Its not even a module, its literally just the chips soldered right onto the motherboard.

If you're looking at a MBP be sure to check the refurb section on the online Apple store. About the only way to tell they're a refurb is sometimes they come in a plain brown box instead of the colored retail box otherwise they are identical to what you'd get at retail (and sometimes better). Having bought several in the past I highly recommend it.

The cost will be cheaper for me new I think I will be getting the 256GB version of the 13 inch.

Soldered-on RAM is another reason I wouldn't buy an Apple computer. That said, I'd use the money you save by getting the lower-end processor and upgrade the RAM to the max, as you can't upgrade it later.

Anytime I've thought I've had enough RAM I've found some situation where I was quite glad I had lots of it. You're not going to need to buy a computer for a looooong time anyway. Plus, it means you don't need to ever have a swap file.