DRLs & parking sensors are probably the easiest to do; I feel a reversing camera is probably overkill for a flat backed car such as the Jazz although a dash cam with a secondary input might be of interest.
DRLs would be best illuminated when the key is in IG1 or higher, so you can still park with the key in ACC with the lights off and the radio on. Fitting DRLs to a Mk2 should be electrically simple but you are slightly challenged when positioning them unless you have an Si.
I'd recommend using a fusetap where possible instead of connecting directly to the car battery.
They should switch off when you illuminate your front position lights (sidelights), dipped beam or main beam, but are permitted to stay on if you momentarily flash your headlights. They ought to be between 250mm and 1500mm from the road surface, the innermost part of the lamp be a minimum of 600mm apart and be at least 40mm from direction turn signals.
You can get some that dim when headlights are illuminated, so they become secondary front position lights but then the whole lamp must be within 400mm of the side plane of the car.
DRLs are not part of the MOT (except for causing a hazard with broken glass lens or exposed wiring, or if they were acting as front position lights) but are ultimately covered by the Road Traffic Act via this chain of regulations. United Nations ECE r87 > EU directive 76/756/EEC > UK The Road Vehicles Lighting Regulations as amended. Manufactures would have to comply exactly, but a diyer should be given some leeway so long as you are not causing confusion or a nuisance to other road users.
When it comes to parking sensors I wonder how much paint you can cover them with before they lose effectiveness if at all?
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TG