Hi
Bolt Seal - Customer’s problem. As stated above, if you mention you have cutters, if there’s anything off about the seal, they’ll blame you! Likewise, if you notice anything untoward, or if there’s no seal, don’t take it off the dock/railhead, report it straight away, make sure your arse is covered!
Paperwork - You’re nothing to do with the load inside the container (unless its hazardous), your paperwork only covers the delivery of the container as a whole so your boss should give you a delivery note which covers the movement of the box from the port to the customer, which they then sign to say you delivered it with the seal intact, or words to that effect plus any identifying booking references.
Load - The load inside is their responsibility. Unless your boss has told you to beforehand and you’ve agreed a bonus for it, don’t get inside. If the customer finds out you haven’t done boxes they might try and pull a fast one and get you to tip it. They’ll deny all knowledge if you get hurt by a falling box etc…
Doors - Stand to one side when you open the doors. If it’s been rough at sea, or loaded by a ■■■■■ boxes may be leaning on the back doors. Crack the doors slightly, if you see anything leaning on the doors, tell the customer, let them catch the box…
Trailer Height - The floor of a container is a lot higher off the ground than a standard curtainsider, so always dump your air before backing onto a dock leveller, even then the box may side above the buffers on the warehouse.
Stability - The centre of gravity is a LOT higher than most other types of trailer. And you do not know what standard, if any, it has been loaded to, so drop your speed by an extra 5-10 mph on corners/roundabouts. Very easy to roll one if the load shifts unexpectedly.
Double and triple check the box number. A Maersk 40 high cube has got several thousands of identical twins. If you pick up MRSU1234567 instead of MRKU1234567 it gets very embarassing at the customer site… Or so I’m told…

HTH