how much iq is needed for the following:

0.just being able to use emacs (casuals)
ex: using built in programs (calc, calendar, etc.)
1.customizing emacs using internet searches (serious users)
ex: setting variables and global keys
2.customizing emacs by configuring packages (professionals)
ex: custom abbrev tables, font locks, fixing broken code if necessary
3.customizing emacs by writing own lisp (hackers)
ex: macros, shell calls, defadvices

do you think its iq or experience, or little bit of both?

serious users are programmers of other languages and often experts of other engineering disciplines (electrical, mechanical, chemical, etc). they have high iq by their trade.

professionals are routine workers with high skills, often dedicated to office automation. these days, reading/hearing english is becoming a requirement, another factor pushing iq upward.

for doing productivity enhancing customizations, i think you need to be a hacker level. this is where the question of iq becomes important; for all honesty, i think you need around 120 (top 10% of population).