Just want to be prepared, with no intention of judging or whatsoever, I have some questions about safety in Warsaw:
I've stayed in Warsaw for a week as a tourist last year and slept in many dorms in central/eastern Europe.
Warsaw is as safe as other European capitals. But I suggest you take several precautions so that you're not robbed of your valuables :
For instance: before going to bed put all your belongings in your backpack. Lock it up, tie your bag up to the bed, hide it under the bed. Keep the key with you. This will protect you against thieves who are most of the time looking for easy targets.
Relating dorms specifically in Warsaw I can't answer but I have stayed in all kind of dorms and never had any trouble. Of course you hear stories and strange things really happen. I remember a guy once, in the next room, whose belongings were stolen. This was classified as a safe hostel by the reviews.
In the end it's up to you and your practices. You are in a shared space with unknown people. You should either carry or secure your most valuable belongings (ID, Passports, etc. included). In principle no one is going to steal a bag of dirty laundry but if you walk around showing your latest iWhatever, etc. someone might actually think it's worth it to break or take your bag/lock. In general the more valuable things you leave unattended/show off the biggest is the risk. Mitigation is up to you.
Side note about hostels: Locks are not always safe. Some are very easy to break. In some hostels you are allowed to leave your most valued goods at the reception.
I was there this year. It's a perfectly normal city. It felt very safe even at night. At least around the center where I spent most of the time. I was staying in the suburbs and even during the commute in public transport, by night, it seemed fine. Again, common sense is the most important thing here. Don't put yourself in strange places / situations and you should be safe.
I live in Warsaw whole my life.
I can't answer on question 1 because I've never slept in dorm in Warsaw :)
With regard to question 2 I think it's safe city but it's worth to be watchful as there are pickpockets. At night you can see many drunk people who can behave loud, sometimes you can see some street fight but I was never afraid someone could beat me.
I had one unpleasant situation at night, when some man forced me to give him my phone, telling that he has a knive. Given that I live here 28 years I think one bad situation is not much but I try to have my eyes at the back of my head, mainly at night.
