noshutdown wrote:1. djgpp or watcom for compiler?
Both, if you can afford disk space 😉
DJGPP will give you a recent C/C++ compiler - GCC 8 (!), but it's protected mode DOS only.
OpenWatcom's compiler is outdated but it can generate 16- and 32-bit EXEs for DOS, Win3.x, Win9x and some old exotic platforms that you'll probably never need.
noshutdown wrote:which is better to use, and generates faster executables?
I'd expect DJGPP to win here because GCC has a reputation of being a very good optimizing compiler. (Watcom also had that reputation but that was ages ago).
2. which ide works with them? just like the vs+icc combinations for windows.
Watcom has its own IDE if I remember correctly, but I've never used it.
DJGPP had RHIDE but last time I checked it was unmaintained and didn't work anymore.
Also, I remember having some problems with DJGPP on DOS 6.22, as it assumed long filenames to be available.
Windows XP is the recommended platform for DJGPP development.