Brand New Van

OK, guys please help me, i just bought a brand new van passanger, i have the fallowing problems, i get a vibration starting from 50 miles and up and it gets worse as i put load on it, then the other annyoing problem that i have is when i brake i have a feeling that somthing is swinging back and forth under the car, now what is that. if you have any ideas on those problems, please tell me casue i feel like i spend $36000 on a pieace of junk

take it back to the dealer and have the problem fixed. if you spent that kind of money it still must be under warranty.