minor means its a fail but the vehicle will pass so it aint failed on the horn,cant tell your exhaust without seeing it but id suggest looking at the mounts your box is fixed to and is down as minor anyway,oil leaks we now have a set limit of x amount of mms leaking over a set period and assuming it meets parameters will be a fail,given you seem to agree with the rest of it and the items youre quoting are mainly minors what precisely is your concern?