1. I will hang out with friends – this means, that there is a plan, but you can suggest me something better (the most uncertain version). 2. I'm going to hang out with friends – this means, that I have a certain plan and I know the details of it, but something can be changed. 3. I'm hanging out with friends – this is also a plan, but that's for sure and I'm not going to change it. a) Is 2 and 3 in present continuous or not? 3 is in present continuous. I'm not as sure about 2. Even though I'm a native speaker we don't get this detailed about grammar unless we're in an English class or we are an English teacher. When I looked it up, one site said it was future simple tense. https://www.theenglishspace.com/grammar/tenses/future-simple-going-to.html b) Am I correct with describing context of these sentences? Generally you have the idea except they aren't quite that clear on their level of certainty. Generally each of them are approximately equal in their certainty in the absence of other context that would establish whether they were certain or not. 3 is the most awkward to discuss future plans because it is in present continuous. That statement would have to be in response to a question like "What are you doing this weekend?" that sentence talks about plans, but is also in present continuous. Of course there are also other ways to express plans. Here's a couple examples: I'm planning on going to the game. I'd like to go shopping.

a) Only #3 is the present continous tense (with future meaning). b) Basically yes. Some useful information here: https://www.ef.com/ca/english-resources/english-grammar/future/