Hey mih26, nothing has changes for quite some time now, so if you read last 20 posts or so, you'll get all the info.
1. It's legal to use.
2. You being or not being a Slovenian citizen has nothing to do with access to the sites. Location is the problem.
Don't want to post links to affiliate site, but if you google PokerPro Slovenija you'll see under "ponudba" (offers) which poker sites are available for us.
3. By far the biggest casino is Perla in Nova Gorica. They have lots of good tournament series with up to 1M€ GTD, which are mostly filled with Italians (which is a good thing). At the time, Perla's Poker Room was the biggest in Europe:
https://thecasinoperla.com/en/casino/poker-room
We only have one landbase and online betting provider run by the government. There are no dedicated betting landbased places if I'm aware, but tons of bars, news stands, most post offices, most petrol stations ... offer their betting. Saying all that, they have horrible odds, offer almost no single bets (you have to make a multi-bet of 3 iirc) and you pay taxes on the spot, if your winnings are over 300€ on a slip. So better to use other online providers as bet365 for example.