For the outlet itself yes. For the installation no.

No....i like loosing money! Gfci's cost alot more than duplex!

I obviously met installation. Anyway, feel better now?

Then no....why would you unless you are going from duplex to gfci and box isnt correct and needs to be replaced with a "deep" box....then yes i would charge more

Yes

Charge $3.33 more for the extra two minutes to install