Kestrel, I wouldn't worry about the writing portion. Your writing proficiency should easily suffice to pass whatever mark engineering schools expect for a respectable applicant. I'm not an engineer, but for economics, the writing portion is only noticed if you got a really low score, at which point the graduate committee might worry that you have serious communication issues. Even then, it's mostly a problem for non-native speakers whose english is considered suspect. I knew someone(native speaker) who just clicked through the verbal section, jotted down a half-assed essay, made mention of his decision to do so in his application, and didn't seem particularly adversely affected by the decision in his admission results.
Suck it up, and take solace in that you will never have to respond to such inane essay prompts again(Unless your quantitative score sucked, and you have to retake)
As for the quantitative, you can probably get away with working through some practice books(you can probably even use your old SAT books)) and memorizing whatever little tidbits you may have forgotten. The only thing you absolutely must do is take the sample tests the GRE folks provide for you. The math is obviously not very advanced, but it can be difficult to do in the allotted time, especially if you're nervous; practice will help with this.
As with any standardized test, the most important thing is to come in well rested and well-nourished. I failed this part my first time(ate way too much and couldn't sleep), and wasn't happy to have to trek to a test centre three weeks later. I didn't do any more studying between the attempts, but I did jump from 71% quant to 92%, and 89% to 98% verbal.
My writing score was identical both attempts, suggesting that my BSing proficiency is not a function of my sleep.