1. I’m not critising nuclear for not being green.
2. Renewables should grow (they’re profitable), but there should be further incentivised growth to help reduce reliance on fossile fuels more quickly.
3. Yes, nuclear is brilliant for voltage and frequency stability. Large turbines have momentum in their spinning mass, when loads are switched on and off they keep spinning the same speed. However there are other options, eg rotating stabilisers, often used on very large ships but land installations are now being made also. These can be built without the nuclear red tape.
4. Replacing existing nuclear plants is always a decent thing to do. You skip over many of the hurdles by building on the same site under the same nuclear permits. However taking money away from renewables to pay for this is questionable at best.

I think Sweden does have some geographical complications, along with a lackluster transmission network. These are much harder to get private investment for. However if there was a decent transmission network then there would be more utility of renewable generation in the north as well as the capability for import of energy from neighbouring countries or even export when Sweden has an excess.

Putting my balls on the table, I reckon if Sweden put all the money they’ve got in nuclear into transmission first and then renewables, I reckon they could switch off more fossil fuels more quickly.