Assalamu Alaikum
It's difficult to receive citizenship. Usually, it is offered to people who have done something remarkable or professionals who can benefit the country. They do use a point system, but again it doesn't make it easier because points are tied to achievements, relationships (marriage, children, etc), time spent there, etc. There's a certain amount of points that must be reached before you can apply for citizenship. Besides all of this, you will also need to renounce your citizenship to your home country or any other citizenships because dual nationality is not recognized/allowed in Saudi (even though there are quite a few people who carry dual-citizenship).
In regards to life there, it is exceptionally safe. Shops close down around 10 minutes before prayer times so you can make it to a masjid. There are many masjids also available inside of shopping centers/malls/grocery stores. Restaurants are closed during the day during ramadan. Food is halal and there is a lot of cultural influences so you can pretty much find any authentic cuisine. Many places are also segregated, so you'll find a restaurant for example with a family section (caters to single women and families) and a male section (caters to males). There's also a very active night life (many shops don't close until 2am, as well as many shops opening at fajr). I know many nonMuslim westerners who have lived in Saudi for years and prefer it because of the Islamic values it offers to their children. It's not a perfect country by any means, but it is a beautiful Islamic country. I'm sure depending on where a person is from, they may face some difficulties or have different experiences. My experiences have been positive alhemdulilah.
With respect to how Islam is practiced, I'd say the government tries to uphold regulations that make worship easier for Muslims. You're not forced to do anything if you yourself are not religious, but you need to be respectful towards worshippers. You won't find bars/pubs, clubs, sexually charged ads, PDA, homosexual normalization, etc. like you would in the west. This doesn't mean, however, that people are ignorant about them. Basically, anything that is considered immoral/haram is not publicized/encouraged/normalized.
Doesn't work like that