Synology DS1817+ advice on setup please

Hi guys. First time synology disk station owner here. Just bought the DS1817 + with 2gb ram. And 4x8tb wd red nas drives.

Primary use of the drive will be backing up my movies and TV shows and streaming to tv. No transcoding required on majority of devices.

A few questions if I may.

What raid/shr setup do you recommend? I'm happy with 1 disk fault tolerance. I initially set up as shr and it took agessssss for the parity checking to finish. How long would it take late down the track as I continue to add new 8tb drives? I really wanna get the right raid/shr format from the start.

I'm currently copying files from my main pc to the NAS and damb it's slowwww. Have I not set something up correctly?

Should 2gb ram be sufficient for the above?

Should I bother with the ssd pcie adapter card?

Any tips on how I can set up a program like jdownloader to download links without needing my main pc on. Or might it be easier to set up a virtual server?

Cheers!