I'm doing a lot of Calculus marking lately, and starting to think about matching up the Ontario MCV4U curriculum with the Khan Academy videos and practice dashboard (sorry, now known as the "Knowledge Map").
Their Derivatives 1 questions provide practice in finding the derivative of polynomials (only quadratics, in fact). The Power Rule questions add simple negative exponents of -1 or -2.
The best place to start for Optimization questions (Lesson 12 in my world) is probably this link:
Unfortunately the Knowledge Map currently stops with taking derivatives, so there are no practice questions on the topic.
This link seems like the best place to start for Vectors:
There are exercises for scaling and adding vectors; so you have to spot 2a and add a and b, but there none where you have to find 2a+b for vectors (and students invariably need to practice the distributive step).