Where can I get this type of 'wood paneling'/'siding'/(name?)
Generically, that's called "Ship Lap" siding. What it is made of is another aspect; it could be wood such as cedar or redwood, it could be pressboard, it could be vinyl or even aluminum made to look like wood. You should be able to tell if it's vinyl or metal by tapping on it. If it's pressboard, you would be able, if you look long enough, to see repeating grain patterns, something that never happens with real wood. 

That fascia / molding and the roof joint needs some professional attention in my opinion. That's a tough spot for a typical DYI project and getting it wrong can leave you with some serious water damage.