The 94/98 is the load rating. You can fit tyres with a higher load rating so 94 or 98 is fine.

The W/V is the speed rating. Again, you can fit a tyre with a higher speed rating so both of those are fine.

You do not need special EV tyres. Any tyres that are of the correct rating (or higher) is fine. You may see a slight drop in range but tbh it is a theoretical drop... I have not noticed any difference in range from the stock tyres.

I have had Continental AllSeason Contact 2 tyres on for the past 6 months and love them. They come out excellent in wet road conditions but slightly below tyres such as CC2 for snow but we don't get a lot of snow in Cornwall so that is why I went for these.

 

So going to W from V means you can now safely drive at 270 Kmh instead of 240 for the V, never tried this as my Niro is not that fast.
Going from 94 to 98 load rating means the tire can now carry 750kg vs 670kg.

So basically you can drive faster with a heavier load.

 

Having gone through this recently with our eNiro we ended up with 98 vector 4 seasons through asda (cheapest). No complaints so far but only 4k miles in.

 

Going from 94 to 98 load rating means the tire can now carry 750kg vs 670kg.

I'm not sure if you meant that the way it sounds, but that 750kg is a per corner weight load - so includes the weight of the car at that axle - and the niro being 1800kg ish, sort of puts a 450Kg load on each tyre before you start.

 

I'll restate, each tire can now carry 80kg more so tire wise you can now have a payload that is potentially 320kg higher.

 

A higher load and speed rating tyre will have a tougher construction, so is likely to have a harsher ride and more noise. Having been using CC+ for 6 years as winter tyres, and after a summer tyre wrecking puncture on M25 last week, I've just fitted CC2. Quieter and smoother than the OEM Eco summer thingies from the factory they replaced.
Now a set of winters for sale.

 

I'm a new (well, new to me, car is 2 years old) E Niro owner, and live on top of a hill in the north of England that rarely gets gritted.

I'd like to replace the tyres with all-seasons. There are lots of posts on here and other sites recommending various models. (Although interestingly I can't actually seem to find one from someone who's actually fit all season tyres on an E Niro).

What's confusing me, though, is when I come to buy them, they mainly seem only to be available in 98 load rating (the sticker inside my door says 94), or in V speed rating (the sticker says W).

How important is it if I deviate and go for 98W or 94V? Can this e.g. affect insurance if I'm not specifying exactly what the manufacturer 'recommends' on their sticker? Could it affect performance, longevity of the tyres, etc.?

Also, am I likely to experience any loss of performance if I go for something like the Goodyear Vector 4Seasons or Michelin Cross Climate 2, rather than an EV-specific tyre?

I recently fitted 4 Continental 98W all season tyres. Tried for Cross climates, but could not find stock nearby.
To answer your questions:
98W is absolutely fine
Too soon to tell about loss of range, I would expect some, but on the plus side, given the recent terrible weather the extra grip is always appreciated.

 

I've replaced my 17" wheels with 18" off the hybrid - and fitted Continental Eco 6 (98W-XL) part worns - at about £40 each. I've noticed no real difference in range, so I suspect that a lot of these ideas end up being very theoretical in the real world. I would say though that there has been a significant improvement in handling, much less body roll leading to more confidence in the corners. Not what you asked about, but if changing the wheels was on the horizon, changing tyres now might be a bad idea.