both the M2 pro and M1 pro support up to two displays, or only one of them?
They both support two external displays in addition to the internal one.
Is a M1/M2 Pro MBP going to be slowed down by having its maximum amount of external displays (2) connected?
No.
The M1/M2 Max will not have its external display support maxed out when connected to 2 external displays, if you know what i mean.
I know what you mean, but you are thinking of this like it's an AMD GPU running on an Intel 16-inch MacBook Pro and that's not how this works. You don't get worse performance on the two monitors that you have hooked up to an M2 Pro than you would with those same two monitors hooked up to an M2 Max.
I think having 32gb or more of ram will definitely be good when having multiple displays connected and while multitasking/processing photos. I will generally not have more than 2 external displays connected at a time, so it should be ok.
Again, you are thinking of this like it's an Intel Mac and that the video RAM is going to be strained by adding more monitors. That's not how this works. You can have 32GB of RAM on an M2 Pro, have your two external monitors, and not lose any performance from that same configuration on an M2 Max with the same amount of RAM. Furthermore, going to 64GB or 96GB of RAM on an M2 Max isn't going to make your output on those two monitors any better while you're not doing any workload that significantly appreciates what Max even has to offer (and again, nothing of what you have described of your workloads tells me that 64GB of RAM, 96GB of RAM, or even any kind of Max chip will be anything other than wasted money and battery life for your workloads).
Will i really see no noticeanle difference when multitasking, like editing/stitching 45MP RAW photos in Lightroom while browsing in Firefox with 20-30 tabs open while also having LibreOffice open?
Extremely doubtful, though it would completely depend on which tabs and just how many 45MP RAW photos you had to have open at a time. 64GB of RAM is still an extreme and your use cases don't sound like the kind of thing that would buckle under 32GB of RAM.
In that situation i think having more than 32GB MIGHT show a noticeable improvement, but surely the jump from 16 to 32gb will be the biggest difference in that situation.
If it's what you want to buy, nothing I say will convince you otherwise and you should probably stop asking for advice if you already know what it is you want to do regardless. Yes, you might have SOME improvement for the one or two really extreme days. Is that worth sacrificing battery life? Is that worth spending more money? I'd argue no, but you're really pushing for it, so maybe it's what you want and I ought to stop trying to convince you otherwise. From what I know of these things, it's wasted money. But you do you.
The Max chips are there for situations where every second in rendering time saved really matters or when the workloads truly are high-end (and it's part of why I don't understand it existing in the 14-inch MacBook Pro). It's the Intel 16-inch MacBook Pro equivalent of the 2.4GHz Core i9 with the Radeon 5600M in that most won't need it, but some will. Basically, if you're not sure if you need a Max chip, then you don't need a Max chip.I think a 16" M1/M2 Pro MBP with 32GB could me the sweet spot for me, and leave some money for accessories and be in my budget (3K) but mainly have much much better battery life than a Max chip, which is important to me.