| The Quikrete? Is it plastic enough to bridge the smaller cracks?

The Quikrete Vinyl Concrete Patcher excels at that. Accept no substitutes!
When mixed thoroughly and with just the right amount of water, it really
does go on like butter. I'd get a small pint or quart plastic bowl - any
empty food container will do - and mix it up in that, a bit at a time. For
the smaller cracks you can just spread it along the crack, feathering out
the edges to have a nice, smooth repair. You really won't even need any
sealer on top of it. What I do when I want a nice, smooth waterproof
surface with it, is to apply it and then when it starts to harden up after
an hour or two (the smaller the application the sooner it will start to
harden), run the smooth trowel over it with some pressure, to sort of
burnish the surface and make it really smooth.

Make sure you wear gloves, and resist the temptation to apply it with your
fingers - the concrete is a bit alkaline and caustic, but also because of
the fiberglass in it, you can get little fiber splinters in your fingers! (I
speak from experience here)

Tim