score:5
To answer your first question, yes they do random checks on laptops and disks, but this is rare. In my last 15 years I only had it once. They suspected some CDs on me and checked them, they also opened my laptop and searched for photos! That's it. They are usually targeting p**n content.
Regarding the internet access, no, there is nothing that will surprise you beside blocking p**n sites and torrent like sites. You will be able to access VPN and anything else. Regarding internet connection and speeds, you can get a sim card from the airport at the same price as in the city, as the major providers have kiosks in airports. Most of them offer 4G at no extra charge, 3G is decent as well if your mobile does not support 4G. Prices are quite cheap as well.
Regarding your last question, there is nothing special. Saudi Arabia is quite open when it comes to media in the recent years, also there is no limitations in bringing electronics for personal use, be it 5 or even 10 devices.
Source: I live in Saudi Arabia and I travel a lot.