As it stands you question is way to broad and vague and hard to answer. This is no place to request for "comprehensive intros".
Generally speaking curves in Blender are kind of a second though. They work but are mainly there as a helper for animations rigging and other related tasks, and less for actual modelling
I do love using Bezier curves as actual modelling tool, and actively work daily relying mostly on curve objects for geometry in Blender. It is an unpopular and exotic method, very few people actually use it, and it is certainly very cumbersome and lacking in features and tools. It requires a lot of workarounds and sometimes convoluted workflows for seemingly simplistic tasks, but it is totally doable, and with practice you will get a good flow going.
That is bound to change for future versions thanks to the Improvements for Bezier Curve GSOC 2016 Project. But if that actually lands in official Blender remains to be seen.
You will find there are no trim/extend/offsets currently, snapping and precision tools are also scarce, and materials and texturing is a pain too.
Importing your curves as SVG from an application like Illustrator or Inkscape is indeed the best workflow. They will come as regular 2D bezier curves.
Avoid filters and effects or any other curve altering modifiers in those applications that create additional geometry; because they will import as garbage and duplicate vertex you will have to manually clean once in Blender to achieve good results and avoid artifacts.
Imported curves often come with varying scale factors, make sure you apply it before proceeding to avoid problems. After applying scale to a curve always make sure you enter edit mode and force-set all vertex radius back to
1 with the Set Curve Radius operator, otherwise it will yield wierd results.
There are two main curve types in Blender 2D (constrained to the local XY plane) good for logos, text, and bi-dimensional stuff; and 3D for anything else like wire or tubular structures.
Inside each curve splines can be either Poly, Bezier or NURBS type. Polys are straight-segment only, beziers have handles, and NURBs are fit through control points.