Play first, then worry about buying gear. Just make sure you bring food, plenty to drink, gloves and actually cooperate with your team. If you don't help you'll just become cannon fodder like almost all rentals.
Polling rate is how often your computer checks the signal from your mouse. Hz = per second. So 1000Hz polling rate means your computer will check your mouse input 1000 times a second.
Vegas 2 was the fucking shit. Can't play it on PC though, FOV makes it feel like you're playing through binoculars and the tools to fix it don't really work
Your basket is stored in your session, we can't see it. Honestly, it might be a better idea to save up more and wait until prices from Ryzen 3 to drop as they're claiming significantly better single core performance which will be good for Source. AMD have delivered on their promises quite well...
Em, I'm pretty sure they are not compatible. A 7650K supports DDR3 RAM meaning the motherboard will only take DDR3 sticks. Ryzen will only run on DDR4 sticks which are not compatible with DDR3 slots.
You'll need to get a new motherboard and RAM.