Praesepe

Had an excellent nights viewing. so now the questions
Andromeda galaxy, Sunflower galaxy etc, were easily visible, but not much detail, mainly fuzzy image in the field of view. I don't have other eyepieces yet, only the 26 mm that came with the scope. Am I correct in thinking - bearing in mind the advice I was given in another post - that I would probably see more detail if I were to use, say, a 30 mm or 40 mm? I think I have this correct, my 2000mm focal length divided by 26 mm gives me about 77X mag. Or is it more likely that I have to go up to perhaps 15 mm?
I always saw pictures of clusters as pretty boring, and not worth bothering about, except for Pleides, but decided to have a look anyway. Hey! C14 is awesome!! I'm going to hunt out more clusters
A bit of a silly question this, but I followed the goto to Praesepe, is that an open cluster? It was something worth hanging around!
Bill.