Basic understanding of Docker

I have never used Docker, but reading about it it seems like it might offer me some advantages. But, before I take the dive, I would like to know if I am burrowing into the right hole.

My use case is this: I have a server, that runs a lot of different applications: mailserver, webserver, cloud, gitlab, etc…

My issue is, I am pretty hestitant to do too much to the entire system, because any type of problem/issue/delay, will affect a whole bunch of systems.

Enter Docker…

it seems that I could create images for each individual system, and run instances of all of them on my server, then setup my system’s webserver to reverse proxy to each individual container.

Immediate questions: Is that a viable setup? Or,is that kind of dumb from a resources prospective (as each would probably need to be running their own databases, webservers, etc…)??

Second options, I setup all the systems once, then create a Docker image of all the running applications, and worse case, can always just run a new instance of the image, if I mess something up?

Any advance, would be welcome.