Many do both, I would say the vast majority. Same regulations and licenses apply, in fact. Simply some companies invest more in casino (which are purchased games from vendors in the vast majority of cases), some invest more in sportsbook. I guess the OP’s case is the former, but it’s not a very relevant distinction to make.

I despise gambling, I don’t gamble myself and I consider it a tax on those who don’t know math. That said, I worked for a gambling company and I know that different companies target different types of customers. Also they have responsible gambling programs that are more or less serious (some of which might be required by regulations). The company I worked for operated in Scandinavia and was sportsbook heavy (vs casino heavy), and had quite serious measures against suspected addicts (immediate block, calling the person on the phone if there were any signs like long sessions etc., proof of income to set limits proportional to income etc.), because it was considered bad for business. Many companies in general are terrible, and especially those who depend on casino games, where the margins are fixed and the dynamics are more prone to create addiction (available 24/7, quick feedback etc.).

No they don’t, at least for Sweden. I remember when they regulated the market in Sweden (I was working for a gambling company at the time and I had to run the security & compliance for the Swedish license). There is no such thing as open market for gambling where the market is regulated (Sweden, Denmark, Estonia, not sure if Norway finally regulated).

As far as I know, a handful of companies got regulated at the first round, some failed and could not operate in Sweden (this might mean you actually need to deny access to users from Sweden - since you do KYC you know) for quite some time (before they eventually managed to get the license).

The problem (why the other user mentions all similar sites) is that the big companies (say Kindred group, Betsson) tend to spin up many alternative brands with different looks to attract different customers.

Also, most of the companies that operate in Scandinavia use the Maltese license, but that works only in unregulated markets (Finland, Iceland and Norway for example - unless something changed in the last 3 years). That said, getting a license once you have another is quite simple usually. The Swedish license for example is easier to get than and very similar to the Danish one, so if you operate in Denmark you can just fill in the paperwork and you should be easily able to pick that one up.