Hello, I hope the following is of assistance.
The two concerns are unrelated, the bonnet lock is a mechanically operated lock and is in no way connected to the central locking. The reason for the bonnet not opening is usually due to the plastic link between the lock assembly and the bonnet latch cracking so when you turn the key it doesn't turn the latch. Unfortunately to open the bonnet in this condition means damaging the grille to access the mechanism, you need to remove the lock barrel then use a long screwdriver to release the latch.
On a Mondeo of this age the locking operating by itself is usually due to water ingress into the driver's front door latch assembly, the latch is integral to the motor assembly.
To confirm this you can disconnect the door motor electrical connector and if this stops the erratic operation change the latch/lock.
I hope this helps but if you have more questions let me know and I'll reply as soon as I'm able to.
Would you be a little more descriptive when you say "access to the mechanism etc" also when you say disconnect the door motor etc - " where is it and how do I disconnect"
as I said previously to access the bonnet latch you need to damage the grille by cutting around the badge, the lock is secured by 2 shear bolts but these are behind the grille. To remove the bolts you either drill the heads off or tap the bolts round with a punch, once loose you can remove them easily. When the bolts are out you can then pull the lock and plastic link out and use a long screwdriver to activate the bonnet latch by putting it in the hole where the plastic link rod was and into the latch then turn it to release the latch. Below shows the lock with the grille removed to give you an idea how it works, you can also see the latch. Once the bonnet is open determine which part has failed, as I said previously it's usually the plastic link rod that cracks where it connects to the lock assembly.
The arrows point to the shear bolts holding the lock.
The door motor is in the drivers door, to disconnect this you need to remove the interior door trim. To remove the trim you need to undo the screws behind the interior door handle and door pull covers as shown below.
Once these are out remove the cover and screw from the door mirror interior trim where the mirror switch is and remove this trim. You then undo the door trim retaining screws and lift the door trim up and off the door, disconnect the electrical connector from the window switches, below is a diagram to assist.
Once the trim is removed then remove the foam weather seal from the rear edge of the door, be careful not to damage it, use a sharp knife to cut the bonding. When you move the rear edge of the weather seal you will see the latch/motor assembly, disconnect the electrical connector as shown below. You can then use the car to see if the random locking continues. The driver's door is the common latch but it is possible to be the passenger front instead but without a diagnostic scan of the GEM you won't know so disconnecting the latches is the only way to eliminate them.
I hope this clarifies things for you.
Let me know if I can assist further.