Welcome,
The main developer manual is in the wiki at
https://librepilot.atlassian.net/wiki/display/LPDOC/Developer+Manual it's somewhat incomplete for a lot of details. If you're planning on submitting changes back to the project the instructions for getting the source code in there are wrong. The rest of setting up the development environment is correct.
The page on github at
https://github.com/librepilot/LibrePilot/wiki/Git-Workflow describes how developers setting up to send pull requests with changes to the project should get and maintain a copy of the source. No one actually works on the main copy of the source, all developers have their own copies and work on them. When a change is ready they generate a pull request aimed at the main repository, it's reviewed by other developers, suggestions for changes are made if necessary, and once changes have been made and it's been approved by at least four other developers it's merged into the main repository.
I use vi and grep. I've used them as long as they've existed, back to early bsd and sysV unix. In fact, I used them even when working on c# projects under Windows, I only used VS to compile.
In the four months or so I've been here I haven't heard anyone mention using any IDE for anything other than GCS and that in a limited way. I think most of the developers are on Linux, a couple on OS-X, and as far as I know, no one routinely using Windows. You're welcome to develop on Windows if you like, it would be good to have someone using Windows routinely. We normally hear about problems compiling on Windows from users in the forum.
I don't think VS can handle compiling with the gcc compiler in the Msys environment. I'd also be worried that it would reformat the code. While I'm thinking of it I should mention, project policy is no tab characters, only spaces.
Tips, lets see...
Use the force Luke... oops, sorry, use the source Dave.
Grepping through the source is probably the best way to learn.
The main makefile has a target to make html doxygen documentation for the entire source tree.
Since you're always working under git version control in your own copy of the source it's easy to make a new branch, experiment in it, and then delete it if it doesn't work or you've learned what you were experimenting to find out. I couldn't tell you how many branches I've created and thrown away like that.
You can tell it's late at night and the forums are quiet, I've rambled on quite a bit...
-Hank