Old PC + New GPU for Recording and Gaming

[-Xerxes-]

Hi all, I have a very old pc and I can’t renew it for a few months but I’d like to get a gpu at least.
My current system is:
i7 4820k 4 core 8 thread @3.9 ghz
16 gb ddr3 ram @1866 mhz (mobo max frequency is that: it’s Asus P9x79)
Radeon HD6950 // 2 gb gpu
Xigmatek 750w 80+ silver psu (Stealth version I think, whatever the difference)

^^ I’d like to make this one a streaming/recording pc instead of throwing it to thrash after I get my new pc so. ^^

My new gaming pc will be smt like that;
r7 2700x cpu
16 gb 3200mhz ddr4 ram
Rx 590 nitro+ Special Edition 8gb or msi GTX 1660 ti 6gb

1-) I think gpu doesnt matter on streaming/recording pc if you are using a 2 pc build so, is it right?
2-) After I get a new pc, can I use this old pc as a 2nd pc to stream and record (gameplay only) at the same time for recording smooth gameplay at 1080/60 fps. Will it be enough or still need to upgrade it?
3-) Upgrading my current pc’s gpu only; will it be enough to record and play (no streaming) on same pc for 1080/60?
Current fav games to record is Anno 1800, World of Warcraft and Total War Three Kingdoms. (Releasing soon so I want to upgrade my gpu for mostly playing and recording it asap)
4-) i7 4820k + 16gb ram and “Rx 590 or gtx 1660 ti”, which one will be a better option for that purpose before I get a second pc to record and play on a single pc? Or not possible to record smoothly without upgrading cpu too?

[Temp name]

1) Correct. However you'll need to buy a capture card for the secondary rig, so you can pass your display output through it
2) Depends on what encoding schemes you use. Should be fine for x264/5, but if you want to use something like NVENC you'll need an Nvidia GPU
3) Again, depends on encoding scheme. Your CPU will struggle if you use x264/5, your GPU can't do NVENC
4) 1660ti. It's roughly 15% more powerful, and it gives you access to the Nvidia control panel, meaning you can get Shadowplay for recording.

Your current system is probably more than fine for light streaming/recording. However if you're trying to do it for a living, I'd recommend spending more than you will on the new build. Also Ryzen 3000 series is coming out in a month or two, so might wanna hold off on the trigger until it does

[-Xerxes-]

Thanks a lot! I totally forgot that new ryzens coming, even I read an article about it 2 days ago lol