So, I hope this is the right place for this, it is really a question about plot structure. So, I've got an idea that won't go away but I'm not sure its feasible: a series of short stories, each focusing on a different character in this sci-fi world I've constructed, which culminates in short story about them banding together to become space pirates. I'm sure something like this has been tried before, there are short stories compilations like Winesberg, Ohio which kind of have an overarching narrative, but those usiually have some kind of framing device don't they? Do you need a framing story to make this idea work? Is it possible to do it in such a way that doesn't rob the stories themselves of tension? Another related question I have is if the stories I'm planning are too large in scope and need to be whittled down? Like, the first one's about a soldier stranded on planet, fixing a space craft, hen coming home to find out his family is gone and he has nothing. That one seems like its small enough to fit into a single self-contained short story. unfortunately, another one is about a person who finds out they're responsible for torturing prisoners of war, their pangs of conscience, doing something about it, and then losing everything because of it...am I right to say thats way too much for one short story?
My advice is to write the stories and then see how they fit together. If they are all individual stories with separate plots there is no reason why tension should be lost. As to the second question about length: it is often surprising how it is possible to contain quite complicated stories in a short space. Also the length of short stories are variable (for magazine publication they tend to be less words, but in a book of short stories it is not uncommon for one to stretch to close to 100 pages). When does a short story become a novella (just looked up the dictionary definition and it is helpfully "a short novel : a story that is longer than a short story but shorter than a novel")? Again, write your stories and edit them well and then when you organise them, edit again.
If you're going for collections, which you almost have to for your stories to connect, I wouldn't worry too much about length. It's not a huge deal if one reaches up into novelette/novella territory. In any case, write the stories first and worry about everything else later. I've seen collections/anthologies set in the same continuity that tell a overarching story before. Some did have framing devices, and some didn't. The Last Wish, from The Witcher series, did a good job of maintaining tension even with its framing device. It was followed by another collection, Sword of Destiny, that lacked a framing device and built on stories from the first collection. So you definitely have options, and like so many things in writing, it will come down to how it's executed.
I would suggest going more of the novella (20-50k) route, but up to you. It definitely works, if done correctly, but I would also recommended strictly sticking with e-publishing.
I think it a fine idea to create a series of short stories that are all related, and especially to have a meta story where all your characters gather. Actually, I love the idea. I have done this on two occasions, in one case, I have three connected short stories. The first two centre around a shuttle crew and some tech engineers, and the third takes place centuries later and 'stars' a prospector. In this case, the stories are closely linked. In the other series, the stories are totally unconnected but all take place in New York. Several of the scenes are set in the same place, and several of the characters make brief appearances in other stories (a waitress, a trucker, a cop all make more than one appearance, like extras in a TV show.) A series can be premised on theme, an event, or even just a location. So long as there is something that links them together, it can work. Also, the length of each story can be variable. One can be relatively normal Short Story length, say 5-6K, while another can be 20K. No problem at all. Take the room you need to tell your story. You can then publish each story as a standalone, or create a small collection. I plan to put my NY series out as a collection, while the Sci-Fi series is available individually. One final thought. Don't second guess yourself. Whatever you want to do, just do it. I think you have a peach of an idea.