Well, you need a graphics card that supports 2 monitors, which literally everyone does, then you usually have to go through a process to get them connected. It's very easy to do, don't worry
Your build def needs a better CPU, an i3 can manage the games, but it'll be a lot more future proof with a better one. Perhaps shave off a few bucks from the CD drive by using an old one?
I guess it depends what games you want, as for sure down the line there will be some great ps4 exclusives, but you could indeed go for an upgrade on a computer now, and get a ps4 down the line when those exclusives exist.