Newbie on SMD. From THM to SMD PCB design and manufacturing
I suggest you get used to creating your own footprints and avoid the
prebuilt libraries. If you use a program that supports 3D it's good
to include accurate 3D models of the parts to ensure mechanical fit.
Through-hole and SMT. 
Manufacturer- is the same as any other part- based on meeting the specifications, expectation for current and future availability, and
so on. Package- I usually consider second sourcing and distributor stock levels so I don't get stuck specifying some dog of a package that gets
discontinued. 
No you can do it with hot air (with a decent tool) or an IR work station. It's not easy to inspect afterward but you can see the part settle into position if you are
doing it manually. Lots of liquid flux. 
Yeah. The vast majority of components introduced have been SMT for the past decade or two, so relaxing the constraint to avoid SMT may feel overwhelming.