Let me get home and ill do a full write up but the basics are as follows

The cap locking mechanism sometimes just needs lubrication or the spring inside has weakened which means removal
Not difficult but not easy either

As for he bumper, need pics as there are lots of variations of bumper but they have additional supports in the wings and are only clipped in under the headlights and are mainly supported by the inner arch liners and under tray

The fan issue may be the fan motor or the resistor pack, all under the dash so...

Yes it's a centre dash out jobbie to clip it back again....

Which means you've got to get he dash out to make space for the radio replacement so kill 3 birds with one stone