It's okay to have a few short sentences in a story. Sometimes, the story flows better if there are two short sentences instead of one compound sentence linked with the word "and."
Using "and" instead of "then." Okay, I went and looked it up in the dictionary. One of the definitions of the word "and" is "then." However, "then" is a perfectly good word. Sometimes it reads better to use the word "then" in a sentence, instead of "and."
Consider this sentence: She swallowed and said, "Hello." Man, that is quite a trick --swallowing and speaking at the same time. I think I'd choke if I tried that. Doesn't this read better: She swallowed then said, "Hello." Doesn't that give you a better visual of the action?
Maybe it's not that big a deal. I didn't notice it when I was reading the stories. It wasn't until I slowed down and started editing them that the "ands" starting jumping out at me.