Question: In terms of read/write speeds, recoverability, and power consumption (e.g. my HDD crashes and I need to have a lab take it apart) – what are the major differences between a 5400 and 7200 RPM drive?
Answer: How long is a piece of string!
The best thing you can do is to take a look at Harddrivebenchmark.net and directly compare the hard drives you are interested in.
As for power consumption, you have to look at the individual specification of the drive in question – the manufactures websites usually list this.
The reason I can not give RW speed is simply there is more to it than that – typically 7200RPM drives are faster, but, you also have to consider platter density as for example, the new mobile 1TB 5400RPM drive can outperform some 7200RPM drives for speed, under some circumstances.