When I did my C&G2391 (which is the exam to show you know how to test and inspect an installation) we had a board which had a selection of electrical items normally found in a house, consumer unit, light fittings couple of sockets etc. We had a 2.5 hour lecture and two people could do the inspection and testing of this board in that time. So we had one hour to test a few items on a board.
We were pushed to find all the faults in that time, so if doing a house it would take more than an hour, however the normal method is to test a sample, if faults found you increase size of sample, if no faults found many consider there is no need to remove every socket and switch if it looks as if all were fitted at the same time, and you have 10 sockets and 5 are OK then one can assume the rest are OK and only plug in tester to ensure earth connected and polarity correct.
The report states all your wiring is on the surface so one can see it all, would seem likely as a result that it has been rewired, and normally you can easy see what was fitted in the rewire and what was fitted latter. And council rewire around here is rip out and replace even if it seems all new stuff, any chandelier was binned and replaced with ceiling rose pendent lamp and tenant charged for it's removal. The amount of really good stuff in the skip was a crying shame.
But it does mean with a council rewire your reasonable sure no hidden nasty bits, which makes the guy doing the EICR job rather easy.
As to IP rating well every item will have an IP rating, you could look at the item yourself and IPX4 means protection from splashes of water from any direction it does not need to have a sticker saying it's IPX4, with Class II yes it needs a sticker, but not IPX4. Depending on the make the fitting of RCBO's will cost around £10 each, some are cheaper some more expensive, and you need around 3 fitting so around ½ hour call it an hour with travel so around £80 worth to upgrade, likely take longer doing paper work than the job. This is assuming they will fit in your consumer unit.
For the installation to match current regulations (which is not required) some of the plastic clips on the wires would need replacing with metal, and the consumer unit also replaced with metal, new fire regulations want cables so they can't fall on firemen and get entangled in their breathing apparatus. So it will never comply to current regulations, but it does not need to, clearly if installed in 18xx when we could use knife switches with exposed live parts it would not be permitted, so saying if it complies with regulations valid at time of install it OK is not quite right, but even pre 1966 installations where lights were not earthed are considered OK if all switches and light fittings are class II and there is a sticker on the CU.
As to NICEIC I am not sure, personally I would think if the report is on their headed paperwork which it is, then they should be ensuring up to standard, I have never read the agreement between NICEIC and member electricians. However there is nothing to stop me from downloading the forms from the IET website and doing an EICR, I would be crazy if I did one without insurance, but there is nothing to stop me. If you were injured as a result of me missing a fault, you could take me to court, and people have been taken to court over a death by the HSE when it has been found an EIC was incorrectly filled in, and it would depend on the electricians qualifications as to if he would be found guilty or his foreman, or in this case NICEIC who must ensure he has the knowledge to do the work, before sending him on the job or issuing paperwork showing it is backed by the NICEIC. But this has always been because the inspector missed a fault, not because an inspector reported a non existent fault. And we see words like "reasonable".
I hope once you get an answer from NICEIC you will let us know what they say.