Yes, I'm very familiar with arXiv, and we also use it regularly to post all our manuscripts as soon as they are ready for submission. I guess it is more and more common for people working in Physics to do this.
As for the the SciPost and Pevo, I wasn't aware of them, but I will surely check them out. Also, the social site Research Gate is a very powerful platform for researcher to keep track of each other's work, and paper authors can even make their full texts available through the platform.
I am usually using InspireHEP that you should know too (this is where I found you ;) ). Very practical!
Yes, I use that as well. ;-)