The main disadvantage is that it’s less automated, and also you don’t get automatic updates without any other package management system in place. If you’re using something like e.g. source packages from the AUR then that solves both those problems and there’s no downsides (beyond extra computational power/time you spend waiting) so long as the package maintainer does their job correctly.
Can it mess with my system in any way?
Not… really? I guess if you’re downloading random tarballs off the internet and running make install without checking the integrity or trustworthiness of what you’re downloading then you could get a virus. But if you’re certain the source you’re getting is legitimate, then I suppose the only way building from source could “mess up your system” is if you mess up your system libraries or something whilst trying to install dependencies.














For Q2: I would recommend your native layout. I’ve not tried US QWERTY but I tried DVORAK many moons ago because it’s “better”, but I found it’s better to be good at one layout than to try split your efforts. If you’re not doing something where speed is crucial, just use what you’re used to. If your keyboard layout is not good for your purposes (e.g. typing a character you need often for the programming language you’re using, is difficult on your layout), you could remap individual characters or maybe there’s a layout similar to your native one but better for programming. But no need to use US QWERTY specifically. Also as another commenter said, typing speed isn’t that crucial for programming. I find I’m always limited by thinking speed, not typing speed.