I don't suppose it matters. Just had a look at both mine and neither have one.
There should only be one in the RH (as looking from the drivers seat) rocker cover, not in the other one. I broke mine about 3 years ago and keep forgetting to add one to the order whenever I've ordered bits so haven't had one for quite some time. Don't think it makes much difference in all honesty.
It's here, http://new.lrcat.com/ and is an online version of the system that the main dealers use. Admittedly it's hosted in Russia, hence some descriptions in Cyrillic as well as English. There's also the official JLR one at https://parts.jaguarlandroverclassic.com/parts/index/brand/key/land-rover but the pictures and descriptions aren't as good.
I've got a Garmin wireless camera wired to the reversing light feed so it displays on my sat nav when I select reverse. I fitted it to make hitching a trailer up on my own a lot easier rather than having to keep getting out of the car and having a look to see how close I'd got (I've got one bruise on teh back bumper from when I got too close....). I've mounted it on the bumper between the two holes for the trailer sockets so it is just above the OE swan neck towball. Wiring was dead easy as there's a blanking grommet beneath the LH rear light unit and a dangling plug there for twin socket electrics with a permanent live, ignition switched live reverse light feed and ground all there. However, it isn't easy to judge the distance from the trailer. It could really do with being higher up so it looks down on the towball and where the number plate lights are would be ideal but installing it neatly and wiring would be a real pain.
If you haven't pulled the rail off or the injectors out of the manifold, then no need to do anything. You'll soon know if any of the O rings are leaking as soon as you turn on the ignition so the fuel pump starts up.
Yes, model year changes took place around September/October time so when you bought your new car on 1st January you were getting this years model not last years. Mine is a 98 model (WA VIN), first registered in March 98 but built November 97.
On the chassis numbers, WA is 98 model year so GEMS, XA onwards is Thor. They go T for 96, V for 97, W for 98, X for 99, Y for 2000, they didn't use Z as it could be confused with a 2, then start with numbers so 1A is 01 and so on. The A signifies built at Solihull but as they were never built anywhere else, they will all have A before the actual serial number.
If the rail lifted off completely without having to really pull, chances are that the rings hadn't glued themselves in place so won't have torn. If they had gone hard they probably would tear so will leak and you'll need new ones but if they are still soft(ish), a bit of lube and they should be fine.
ERR7309 is correct for Thor, RTC5679 is for GEMS and EAC2414L is correct for both. I've found that the O rings are usually fine unless they get torn although I usually lift off the inlet manifold with fuel rail and injectors still attached so don't touch the O rings (unless I try lifting the manifold by the fuel rail and they pull out). Red rubber grease on them is a good idea when putting them in.
I suspect there's very little difference, the coolers are interchangeable and the fittings are almost in the same place. Probably just a slight difference in the bends so they fit neatly in the notches in the radiator surround.
Welcome, glad you got here. That isn't basic, I've got no leather, no cruise, no sunroof and no electric seats, but I have got the headlamp wash wipe and front fogs. Mine came with the options that plod thought useful when they ordered it but none of the superfluous stuff. But what is there all works. Then again, my other one has everything.....
Yours sounds like a lot these days. Well looked after for a while but when they become cheaper get bought by people that don't understand them and don't look after them. Then it can go one of two ways. It will either be bought by someone who returns it to how it should be or it gets further neglected until something serious happens and it gets scrapped.
This page http://new.lrcat.com/#!/1234/91427/91612/7253 gives the part numbers for the hoses for a 4.0 litre. 4.6 is different as it has a larger cooler.
I think mine have reduced themselves to the bracket and a small bit of remaining heatshield. I've thought about replacing them with a bit of ally sheet but it's never got too hot even when driven at 70 mph for hours on end.
If it passed emissions on the MoT I don't believe the 7 mpg, did you zero it before setting off (press and hold the Info button) as sitting around idling will make it read really low.
+1 on centralising the steering box. There's a lug on the side of a plastic disc on the input shaft into the steering box with a matching lug cast into the body. They should be lined up when the steering is straight ahead or it will pull to one side all the time. If that is out you adjust on the drag link, if that is correct you adjust at the steering wheel.
The cheap cases are the ones that allow the circuit board to move around. It doesn't come with the little strip of metal that goes in the battery holder which is the bit that causes most problems with bad contacts.
You can get the cheapo Chinese ones on eBay but they aren't that good so the circuit board can move around inside making them intermittent. Your best bet would be to send it to Jon and get it fully refurbished, see https://www.ebay.co.uk/itm/402718362924
It'll probably only need a light tap. There is one tooth on the reluctor ring that is taller than all the others so that one pushes the sensor out to give the correct air gap. At one of the Summer Camps we had a Marty's workshop, one of the guys had the ABS light on when we drove to the hotel. Nanocom said it was one of the front sensors so put the steering on full lock, got underneath and tapped it with the end of a wheelbrace, ABS then working perfectly.
Simplest fix of them all, hit the ABS sensor with a mallet to knock it in further.
Batteries are on the way out now anyway, Hydrogen fuel cell is the way to go. https://www.toyota.co.uk/new-cars/new-mirai/meet-mirai#1. It was Toyota that started it all with the Prius so why not?
Plus the fact that an ICE can be run on Hydrogen too so it's a dual purpose fuel.
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Same with UK unless the trailer has LED bulbs without resistors fitted as they don't draw enough current for it to know you have a trailer plugged in.
All that will do is increase the length of time it takes to change over. Parallel is only really needed if the heater system closes off the flow when you don't want heat. I was checking something else on mine with the Nanocom earlier today and for a coolant temperature of 83 C the heater matrix temperature was at 76 C, so that's 7 degrees being lost through the vaporiser.
My local Timsons didn't have the blank in stock but ordered a couple in and cut me a spare key. If I was to ever lose my fob then having a spare key at home wouldn't be a lot of good to me if I was miles from home so it's carefully waterproofed and secreted under the car. Even my MoT tester didn't spot it when it was up on the ramp but I know where it is.....