This is where you’re going wrong. You can’t learn EVERYTHING and be great at it. Given time, you can do it and be GOOD, if you’ve got the mind for it, but few others will take you seriously. You should pick a field and specialize in it. CCNA is one route. MCSA is another. Or do both! But keep your certs up. That’s mainly what the business community and HR will look at. Also, stop thinking of servers of some all-powerful, high and mighty, God’s gift to creation. A server is JUST a better-built computer, usually running a slightly modified desktop OS. That’s it. When I took my first one apart, it was, “This is just a big desktop. Let’s hop to it!” That’s all there was to it.
And Google all of your questions! You’ll see points and counter-points. You’ll see people calling others idiots for choosing ‘Brand X’ or ‘Technology Y’, and others, just as qualified, using exactly those brands and technologies. Everyone has their own experiences and biases.
Actively monitor a server? You can use a third-party monitoring tool, or remotely look at the WMI data. That’s it. Smaller operations, you react and put out fires a lot. If you can get ahead of the curve and proactively watch things? All the better.
Manage a server? You make sure the backups run. You add or delete users. You watch things to make sure it doesn’t run out of space or RAM. If you’re good, you figure out scripts and such to automate things. I remember asking a server admin at a large company, “That’s it? That’s seriously ALL you do?!?” They just laughed and said, “Yup. Make WAY more money than you do, too!” 
Server hardware? Most of it is over-powered these days, anyway. You size them for VM loads, and most of that is simple math. You want four servers that need 64GB RAM and 4 cores each? A server with 256GB RAM and 16 cores will do the trick! Short on cash? THEN you have to pare down and figure how you’ll cut corners while keeping performance up.
RAID these days is the same as it’s pretty much been. RAID0 for a gaming system you don’t care losing with a drive crash, RAID1 for small, redundant systems, RAID5/6 for SSDs or smaller <900GB GOOD hard drives on a strict budget, RAID10 will do for almost anything else. RAID50 and the like aren’t really done all that much. There are more schemes now. Again, just Google them!
WSUS is if you don’t want a lot of bandwidth used, or if you want to control how often systems update and what they update to.
Actually, a ‘System Administrator’ is usually a Linux/UNIX server admin. We just use the term to portray an IT Generalist. Those of us that are good at everything. For the work that I do, others have wondered why new companies they go to have separate people, or TEAMS, to do the same amount of work. The overall arc to this? KEEP IT SIMPLE, STUPID… (KISS
) I’ve seen IT people crumple in situations, and it’s because they did the opposite. But pick a tech you want to pursue first and go for it. Networks are always a good bet, so that if/when you branch out later, you’ll have a good understanding of them whatever else you end up doing.