I figured I might as well mention this since I don't think it's covered anywhere in a manual or tutorial. If you've already discovered it, good for you
There's an easy way to select multiple objects, faces, edges, and points by clicking and dragging while holding the CTRL key. Naturally the select tool
must be active. Try it out if you haven't to see its usefulness!
On a side note, holding CTRL while knifing only allows you to knife faces point-to-point on the same face (splits that face). Doing this does not knife any other edges or faces. SHIFT on the other hand only cuts edges and won't connect with pre-existing points.
