Valve have said there won't be a Steam Deck 2 for at least 2 years as the chips and stuff they want to use are ready / available yet.
The 1TB Steam Deck has some kind of slightly different screen which is supposed to reduce reflections yet its reported to be a bit less vibrant than the 512GB version (I have this one, the screen is great). I bought a 512GB micro SD card. You could buy bigger too but obviously it'll cost more. Whichever Steam Deck you get you'd enjoy though.
Internet works great, the WiFi is upgraded from the previous machine apparently.
I run Game Pass on mine and can stream games - it works surprisingly well! All Internet connection dependant of course, but my connection isn't great by any means yet this works for me. There's a little bit of fiddling round to set it up but there's official instructions from Microsoft and lots of YouTube videos. It's a 5 minute thing to get it going but you have to type in things very carefully. We'll worth it though.
I don't know anything about PlayStation tbh, sorry.
They're surprisingly wide but not heavy I don't think.
Good luck anyways