THe order in which you assign qmake variables does NOT alter the resulting makefiles (so it does not alter the compilation...) EXCEPT if some assignements make use of the $$ operator and reference other variables of your project files OR if you use = or ~= assignement operators. Indeed qmake interpretes your project file as a kind of script that fills a variable map and THEN generates the makefile.

Hope this helps.

P.S : include() is a function, not a variable. As far as I know it is equivalent, in term of control flow, to embedding the content of the included file at the exact location where your include() directive is. The $$, = and ~= considerations still apply.