I was actively working on Genius Horizon OS until I paused the project for some reasons, now when I decided to return to work, I took a look on the current code and features I realized that my OS now is very basic and featureless, so, I decided to re-write the whole OS or actually write a new one from scratch - again

Now I have many ways to go with in the new design keeping in mind that I am very fan of Rolling Your Own staff.
-The development environment:
Previously I was using Visual Studio IDE, compiler and assembler. I am very familiar with VS and tweaking it. But when it comes to writing a new OS that I aim to be self-hosted, I think that VS here will be somehow a bad idea here, do you think so?
If we come to gcc, tbh, I don't have any experience with gcc staff and other gnu related tools due to that all my work previously was with VS and nothing forced me to use gcc, do you think that it is a good idea to use a tool that I am not familiar with to build an OS directly?
-The language to be used:
My previous attempt in OSdev was in pure C and Intel syntax assembly with nasm. Do you think that I should shift to C++ or it is OK to go with C especially that I am more familiar with C?
-The primary booting device:
Previously I was using floppy disks (awful headache

What do you think ?
-Kernel layout, subsystem, userspace and such staff :
As I mentioned above, I like rolling my own design, especially that I am developing an OS, so I am free to do what I want.
What do you think , should I follow available archs or to roll my own to meet my aims ?
-Primary executable files for the OS apps:
ELF or EXE ?!
I would go with EXE honestly if I chose to go with VS as the primary IDE.
Those are the criteria that I thought about for now, I will be very thankful if someone guided me to other things that I should also consider while designing my OS.
Thanks in advance.