PLANS: I am a 28yo male & on Cristmas Day Im supposed to fly out on Korean Air with my buddy to Bangkok, Thailand- with a connecting to South Korea. My trip in total is scheduled for 22 days. We have two nights booked in Bangkok upon arrival and then the idea was to travel (by bus) to Koh Phangan for the full moon party and to stay at the Sunrise Resort for five (5) days. I heard the way back can be brutal to Bangkok so he suggested we fly back, but Im not sure what the costs are and if it will be worth the trip to Koh Phangan, when my trip is 22 days. The third destination on the list is Pattaya (south east of Bangkok). Accommodations are not booked after the Full Moon Party and Im worried what a typical day traveling spending money will look like so I can budget for the 22 days. INTERESTS: I would like to see some good parts of the city and temples.. I like the idea of partying like this for new years but Im not sure I would travel that far just to party with other tourists on a regular full moon. TIPS: What are some things I HAVE TO SEE?? What are some tips, from your travels to Thailand that would help me for the first time. Most of the responses Im anticipating will tell me not to worry and Ill just say I love my buddy that Im going with… but his judgement is a little off sometimes. BUDGET: 1500, USD is that enough??

LUGGAGE: Im bringing my new go pro with one of those selfie sticks to capture the trip. My buddy was talking about bringing a laptop.. I said for what? That brings my to my next question.. What are my MUST haves in my luggage… whatever it may be and last I was wondering about travel insurance? Scam or helpful? That brings my to my last Topic. Here is what I have:
Teva sandals
Adidas Shoes
Sunscreen Go pro hero 3 silver Several changes of clothes.. shorts tanks etc..
??? Dress Shoes ??? and Jeans for the temples??
Passport and flight info
I have NEVER done something like this before!!! Please help

Safety: My buddy is from LAOS so he can speak Thai, but Im just worried about my general safety on the trip? Should I bring something for self defense??

Thank you let me know if you have any questions and Ill clarify!