Some springs are short enough that you don't need to compress to put them on, but the stork springs will fly off of the shock if you don't use a spring compressor.

It's a myth that coilovers only help if you cornerweight. Coilovers are a more solid and more tunable suspension that are less likey to bottom out due to shorter stroke damping units. Just about every coilover will come with rose-jointed top mounts and integrated camber plates to correct for lowering. I have Megan Racing units (same as Apex N1) on my Legacy and the ride feels the same as a Legacy GT with much better handling and more adjustment capability - They are in the same price range as a set of Tein HE, which are now discontinued.

It depends on what you want from your car. If you just want a mild lowering an hardly ever take your car to the track or drive it hard, springs and a camber kit will satisfy you. If you really want to extract more handling performance from your car, coilovers are the only way to go. If you lower more than an inch or two, you will want to go with short stroke shocks to avoid bottoming (and damaging) your OEM shocks.

Coilovers can definitely be installed in a driveway in a few hours, while I would argue that springs on OEM shocks would require the use of air tools.

Hope this helps. If you are interested in a set of Megan Racing coilovers, www.XATracing.com can get them for you.