Couple of Computerphile videos featured Brian Kernighan [1], which I also enjoyed. I particularly liked the Bell Labs one where he talked about what it was like to work there, pretty fascinating stuff.
For the software side, I would most likely use mailinabox [1] or sovereign [2]. They both setup mail servers for you with reasonable defaults using Ubuntu and Debian respectively.
Ars Technica has a great 4-part guide [3] on setting up a mailserver yourself.
iTunes U has some amazing lectures. Gilbert Strang (MIT) has some video lectures (MIT OCW) on linear algebra. They are a bit dull, but they are pretty decent.
I also recommend academicearth.org.
If you are near a university, take a class "mathematical physics". These kind of classes usually cover a lot of undergraduate material in a semester and are offered by many physics department. They usually use "Mathematical Methods" by Boas as a text.
Do you equate people who have achieved great success/heights as geniuses? Do you think Tiger Woods is a genius golfer or that Warren Buffet is a genius investor?
Or do you equate the kind of people who for example, listen to a piece of music they have never heard before, once, and can play it flawlessly the next moment. I think these kind of people are more savant than genius.
If one is dedicated enough, I think the best way to go about it is picking up textbooks (make sure to pick the good ones - reading reviews on Amazon) and powering through them.
There are quite a few resources out there though to supplement the textbooks, like course websites, old exams and opencourseware (MIT and Stanford have some amazing videos on iTunes U, Berkeley has a channel on YouTube)
[1] https://jekyllrb.com/