Although it comes in a can, it should be stored cold. If you open it and it looks something like mushed up tuna, as I have seen in some Youtube challenge videos, something has gone terribly wrong. Don't eat it!
Unless you have a can of filets, you should gut and clean out your strömming. Keep the roe if you get a lady fish, the rest of the innards you don't want. I have never seen a properly gutted strömming on Youtube. And of course you get the bones out. Unlike pickled herring, where the acidity softens the bones, the spine of a surströmming is not pleasant to eat.
Eating it indoors is fine. You don't need a bucket of water to open it in. A napkin to protect against spray due to the pressure is fine. Pros just tilt the can slightly and open it without even a napkin. The smell is admittedly potent but it's not a chemical weapon. All the crazy stories about how the smell is impossible to get rid of are told by people who don't eat it themselves, in my experience.
The taste is obviously quite strong. A little bit goes a long way together with plenty of bread and potatoes. It is also very salty, so you will probably want to drink something.
And most importantly, expectations matter. Presentation matter. The reactions of people around you matter. If you have brought a can of the most disgusting food in the world, a bucket to barf in and your mates are giggling and ready to record your reaction, you will most likely not enjoy surströmming.
However, if you come to a set table, where the strömming is presented as actual food, you can feel how the other guests are enjoying themselves and you are also there to do the same, you are much more likely to actually do so.
I have been present several times when people have had surströmming for the first time. Some people liked it, some people didn't. Most make a comment about the smell. But they have all tasted it without hesitation. Not a single one gagged the slightest. None of them were in it for the thrill or the challenge. They were just guest there to enjoy a dinner with friends.