i have yet to do it on my car, but i've replaced the struts on a few others (89 Thunderbird / 89 MX6 GT) and it's definetely a DIY job. Consult a repair manual for the blow-by-blow, but it should be pretty self explanatory. You will need to rent a strut srping compressor, but that can be found at almost any parts store for cheap. as far as replacing both goes, it's a good idea for a couple of reasons. 1 is the old headlight analogy: if one's burnt out, the other isn't far behind it. another reason is that the ride characteristics of the car tend to change as a shock wears. if you only replace one, the rest of the car will be kinda soft while that corner will ride a little stiffer. it won't necessarily hurt anything, but it will affect the ride and driving characteristics of the car.
Mike