Writing this on an i3 FW 12 with 32 gb, on OpenSUSE Tumbleweed (pretty fast and optimized distro all in all) with Gnome (obviously not the fastest and leanest DE out there).
For general computing it’s perfect - not laggy or slow at all, and fun to use. I was worried it’d feel like a serious downgrade from what I’ve used to with larger, more expensive laptops, but as long as you don’t do anything that really taxes the CPU (it’s obviously not meant to be a “grown up” gaming or music production laptop), it’s a snappy little machine - even with the generations old low-end CPU.
I’d be equally fine with 16 gb of memory, 32 gb is overkill. On the other hand, I feel like 8 gb might often be a performance limiting factor these days, so that’s one thing I’d consider carefully, if you can eg. find used/recycled memory for cheaper. Especially if you always tend to keep a bunch of browser tabs open like I do. I exceed the 8 gigabyte active memory boundary all the time with this particular computer in normal use, 16 very rarely if at all, and 32 practically never, so I’d guess anything under 16 gigabytes would make the laptop feel a lot less fun to use for me and OTOH anything over that is actually a bit of a waste of money for now. YMMV - you can always be actively mindful of the memory use and do with less.
As for the other questions, some people adapt to smaller screens really easily, others struggle. I’ve now got 16", 14" and 12" laptops around (the biggest one being the work laptop), and don’t find there’s much of a difference in general use. It’s only when I do something that really actively needs screen estate - eg. making music or professional software development - that I actually really want a bigger screen. For web browsing, sketching, writing, light gaming and so on, 12 is as good as 16, for me with my eyesight at least.
Bear in mind that the common complaint here about the FW 12 screen is that the color profile is kind of noticeably off. Eg. the red end of the spectrum looks more like orange. So if you’re serious about art, lack of color accuracy could be a big minus. If you’re more into just doodling and sketching, it’ll probably work in a pinch.
I don’t know what the used market is like where you live, but two months ago when I bought mine, I decided to get just the bare bones DIY FW12, and hunt both the memory and SSD used on a local online marketplace in the small country I live in. That’s what I’d recommend everyone to try out in the current crazy memory market.
Ended up getting a 32 gb SODIMM for the same price 8 gb would have cost new, and a 2 tb 2230 SSD for the same price as 512 gb ones cost new these days. I’m sure you can still get eg. a 16 gb memory stick with the correct spec, and a smaller 2230 SSD for a much more reasonable price used, unless you live somewhere where the market for used computers and tech is very scarce / close to non-existent.
Edit: also, the Ryzen 3250U is a couple of years older and benchmarks very clearly slower (both single and multi core across different tasks) than the particular i3 in the FW 12. In that sense, as long as you get enough memory for your own use case, I think you’re most probably going to get a very noticeable speed up.