Yes the ETP is on the outside and in the case of a fibre connection is used to transition from an external fibre (either fixed or blown) to an internal fibre (normaly a composite cable containing fibre & copper circuits) which is taken into the house and terminated where the ONT will be located.

Not always. In our case, we have the same fibre all the way from the cabinet through to the ITP. No joins in the ETP.
Can not comment on fibre in the roof as ours is under our wooden floor. In that case, it is run in a white microduct stapled to the floor joists.