1.) my writing isn't super strong either so may be better off asking someone else 
2.) Either approach is valid, hard to say which is definitively better. Like, for example, if you're only going to be working on 1 story at a time regardless (i.e. not doing like 25 pages of the longer story, then another 10 page poem, then back to the longer story) having them all in 1 place wouldn't matter much. But if you wanted the series to have uniformity in length then having these much longer stories might break that flow and be better served in a different series. And even then, at 50ish pages you could make an argument for either making each one its own standalone series or making another collection of one-shots.
3.) Not too knowledgeable on this either, but I'll drop @faeriesandents as a pair that has some experience with printing
(among others).