Within the university, there are various activities that students may participate. There are departmental activities (Computer Science Department may have Hackthons, ACM student chapters etc), college related, international student related (International Student Organizations organize fairs, dinners, excursions etc that are more catering towards the specific community while International Student Offices organize events for all international students), or university related. Visiting the relevant websites for relevant events will keep you updated.
Touring the US is fun. The US is a huge country with lots of things to do. This is one of the fun experiences that every international student must participate in. Making sure that someone knows where you are going, carrying appropriate identification documents/cash/insurance/mobile, and planning ahead of time (for tickets, lodging etc) are important. Celebrating and having fun at the dorm or the apartment is natural. As long as your celebration does not cause any discomfort to your neighbors, you are fine.