Unless it is a very hot day you don't really notice it. I sometimes put it on when I feel like I might sweat throughout the day but it isn't really necessary and no one really cares.
So they should starve? The religion itself says self harm is forbidden. If it comes between disobeying religion and self harm you should choose disobeying religion. For example if you are starving you are permitted to eat non halal food.
C++ people still change. Normal people update their version when new ones come out and adapt their pratices to "Modern Idiomatic C++". While a ton of C developers have been using C89 since the 90s.
Arch because https://wiki.archlinux.org/title/Arch_is_the_best
Enough said.