Hi,
I know how you feel. It is tough to be "normal" when you are smitten and have the new excitement feelings. I would go to the class and continue on as normally as possible. I hate when guys do that too with the phone calling or not calling. Personally I would not say anything to him, but then again, I would not pursue this guy too seriously either. If you two have not decided to be exclusive - and I am gathering that you haven't because this is new - then I would start to see other guys. I would just go out on dates - nothing serious. I would be available, but not too available to any one of them.
It is nice that he has paid for things, but that does not necessarily indicate anything serious either. Men like to feel like they are good providers and he probably likes to make these gestures (otherwise he would not do it in the first place). I think it is a good sign that he has made these gestures. It also does not make you obligated in anyway to him either. Unless he has stated that he wants exclusivity, then don't worry about taking the trip or going to the event. He probably enjoys your company, but since it has only been a month he probably wants to take his time and see where things go.
It is your choice, but I would not completely drop him for the not calling thing. I would not make a big deal out of it either. Just see other people and then you won't be thinking about his calling or lack of calling too much and you will have a lot more fun.
Forgot to mention about the making plans thing - I always make it a rule to never accept a date invitation from a guy after Wednesdays - even if it means I sit in that night! #1, the guy had Monday to recover from the weekend and think about calling me, #2 Tuesday would be the optimal day if he got my number on a Saturday, #3 Wednesday is the deadline for a Saturday invitation - Friday will be "filled". My reason? Because I do not like to feel like I am the last minute option for a guy. Now I may be weird about that, but I want the guy to know that I am the priority, let some other girl be the last minute option. The only acception to the rule is if the activities for the last minute invitation involve an event. For example, he could call that Friday and say "hey, I just got 2 tickets to a show, sporting event, etc..." then the rule can be bent b/c I would not want to miss out on the event and these types of dates can happen due to last minute ticket availability - ie a friend cancels etc. I do not feel like a list minute option there because he did in fact consider me to go. Plus it is hard to get tickets to really cool stuff haha!