.net is a framework yours seems to be messed up or not correctly installed. I don´t know why you get the csc.exe error but there are many People out there that experience this and have different Solutions. You got to look it up on the internet and see what fixes it for you.
https://www.google.de/search?q=csc.exe+error
Unless you reffer to another error x) Im a little confused now.
You are using a Oudated Server Target file. Whatever guide you are following is Outdated 
use the one from the wiki. The virtual function you try to override there does not exist and thats what the error is telling you.
Depends on your Rig. On my Rig it takes roughly 40minutes. A friend of mine has updated his Rig recently it takes around 20 minutes. On my couple years old Laptop it took around 90 minutes. Never heard of someone who needs to take more than a day =)
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