keep on practising, and if you have time left over at the end, go straight back to the questions about constant.
some people like to substitute the numbers into the equation and THEN re-arrange it, however I find that it confuses me so I rearrange the equations and THEN substitute the numbers in.
you come across like you're panicing tomorrow. stop you'll do fine
momentum hasn't come up yet so I think it will. 2011's paper was HEAVY with radiation & isotopes (it was horrible!) so I think it may not be as much this year. but i dunno