i couldn't tell you if your card can go with nvidia-340 i mean theoretically it can but you'll need to figure out how to manually install it since the driver manager will probably not offer you the nvidia-340 but i may be wrong. do you have that option?
i don't know why i have screentear. i never had it in any distro or desktop, only in cinnamon19 but even that only when i play games that have too many blinking lights and for some reason the command removes it.
i don't even use the command for notear. i'm sure there has to be a remedy but i don't have the hardware to test. i can suggest you install a mainline kernel, but you really need to have a Timeshift snapshot to go back to in case things go bad. i use the last kernel 4.17.17 from ukuu
found out that kernel 4.18 destroys snapd, maybe they fixed it but haven't tried the latest.
maybe your driver update didn't work because you were using kernel 4.15.
on the other hand if you decide to install XFCE the tear should be gone in any driver and if not the command will surely remove it. it's what i use now. i installed XFCE on top of Cinnamon