Hey!
I went in my 3rd year. In Scotland, studying abroad in your 3rd year is pretty typical, but they also offer studying abroad to 2nd and 4th years, too.
It'll vary a lot depending on university, then depending on department and even depending on what course - best to check with your department directly.
I did indeed!
One of the best things with studying in the US is you can effectively take as many classes as you wanted. I had all of my mandatory classes to satisfy my home university but I had room to add in a couple of extra classes. One was an introduction to learning Russian just because it was freely available to me. I also got a research position whilst at my host university.
I'm still in touch with loads of people from my year abroad!
I met people at my accommodation, events run by my accommodation or university, in my classes, in sports clubs, through other friends, etc, etc. When you get to your host university they'll almost definitely have an international orientation day or week. This way you'll meet a ton of local and international people straight away. It's quite like starting uni again but with more experience and help!
I decided to stay on-campus in a 2 bedroom apartment - it was incredibly nice but typically accommodation in California is a bit more expensive, so make sure you save up.
There are so many options for housing so you'll easily find something you'll like. Where I was, all the accommodation and nearby accommodation was for students at that university, set up sort of like a resort.
Let us know if you have any other questions!
Scott
Undergraduate Rep
School of Engineering