A few thoughts based on my experience. I assume this is your first
ocean crossing so it is too be expected that you will want to really organized. Perhaps you have gone
overboard in some respects. Comments on your topics
Rudder loss - highly unlikely with a boat like your Shannon but a cable break is entirely possible. If you have a
wheel a cable break is a possibility. I inspected the
cables before leaving to cross the
Indian Ocean, had a break in the only place I would not get at to inspect. Try out your emergency tiller in at least moderate conditions. How does it attach and at what angle. Is it long enough to be used by hand or do you need to rig tackles. Forget about
oil bags, you won't use them and the
oil you would need would take up too much space.
Rigging - Inspect the entire rig carefully before going. Have one cable long enough and strong enough to replace any of your
cables and mechanical fastenings. In this day and age,
Dyneema way make more sense. Think about how you would jury rig in various circumstances. A good thing to do during night watches is to play, 'what would I do if ...'
Most important for avoiding collisions is to keep a good watch all around and at the electronic aids. If a vessel will get close to you, give them a call just to say hello and to make sure they see you. The officer on watch is likely bored and does not mind a chat.
Falling overboard - Even if the
wind quits (and where you are going this is highly unlikely) there will still be a sloppy, irregular swell. You are much more likely to take a tumble in these conditions than when it is sporty and you are being careful.
Injury - You need perhaps four levels of pain killer ranging from Advil on up to handle different situations. We eventually ended up with four kinds of antibiotics since the ones that are good for gastro do nothing for a toothache. We had them for skin, gastro, dental and respiratory. A surgeon friend recommended a skin stapler when I asked about suture lessons. If you know a surgeon you probably can get a free one since they are often left over (unused and sterile) after surgery.
Knockdown - highly unlikely where you are going and I assume when; spent some time visualization what could fall and where. With a Shannon chances are that
hatch boards and floor boards are heavy enough you would not want them flying around the
cabin. We were only knocked down once. The large, heavy chart table opened and ours digital
camera ended up on the floor soaked in seawater.
Self-steering - If you have a reliable vane and
autopilot you do not need a second AP since the one you have is really just a backup for the vane. Make sure you can use the vane effectively before you go.