You don't need a clicker if you use a marker word. But go ahead and use one if you're excited about it.
My dog started this habit of jumping on recalls as well. What I did was I started teaching her the recall again using a treat to lure her. I made sure to lure her with her nose down so that she did not think of jumping. At the last minute I would lure her into a nice straight sit and mark that and reward. Maybe your dog is jumping because she does not know how the recall is supposed to end, and jumping is fun? Anyway if my dog jumped I would just say "nope," and end the session, making a big show of putting the treats away. It seems to have worked as she recalls and sits right in front of me now.
I don't have any advice on jumping on guests since I have never had to deal with that problem. All of my dogs have been somewhat reserved.