changing multiple permissions with one single command
You can just list with commas.
$ ls -l file
-rw-r----x 1 tomasz tomasz 0 Aug 12 22:24 file
$ chmod u-w,u+x,o+r file
$ ls -l file
-r-xr--r-x 1 tomasz tomasz 0 Aug 12 22:24 file
You can also use the = syntax.
$ chmod u=rw,g=x,o=rwx file
$ ls -l file
-rw---xrwx 1 tomasz tomasz 0 Aug 12 22:24 file