The Digidesign AIR Spring Reverb plug-in is a free piece of software that comes with the newest version of Pro Tools, which is Pro Tools 8. AIR, which stands for Advanced Instrument Research is under the Digidesign name and this plug-in and the other AIR plugs can only be found in Pro Tools 8. There is literally nothing to the process of installing the AIR Spring Reverb plug-in since it gets installed automatically once you've gone ahead and installed Pro Tools 8. Most of the AIR plug-ins share a similar looking interface, and the Spring Reverb has one that is easy to follow no matter what sort of level you're on. It simply has a series of knobs that includes parameters for pre delay, reverb time, and mix, as well as reverb diffusion and width falling under the reverb section, and a low cut option under the EQ section. That's pretty much all that there is to it, so I don't think you need and manual and I don't believe you have a choice either way as I don't think they make one for the AIR plug-ins.
I just made the upgrade to Pro Tools 8 LE from 7.4, and I'm very glad that I did so as I find it to run smoother in addition to all of the great new features and plug-ins that weren't available before. I'm running Pro Tools and this plug-in on a Mac Book Pro that has a 2.2 Ghz Intel Core 2 Duo processor and 4 GB of RAM. I run Pro Tools with a Digi 002R for the most part. As far as running the Digidesign AIR Spring Reverb goes, I haven't had a problem whatsoever. I should say that I run all reverbs and delays on auxiliary channels to save processing power regardless of if I really need to do it or not. It's just a good habit to get into and helps a lot when you want to use the same reverb plug-in on a number of different tracks at once. As long as you've got the bare bones in terms of being able to currently run Pro Tools smoothly, this plug-in isn't one that should be a problem for you.
While I'll never complain about a free plug-in, the Digidesign AIR Spring Reverb isn't my favorite of the free reverb plug-ins that are found in Pro Tools 8. Don't get me wrong it definitely has a good sound and is useful, but I enjoy using the AIR Reverb and Non-Linear Reverbs more than this one as I find them to be a bit more versatile. Having said this, the Spring Reverb has a particular sound that isn't really possible with the other ones. Don't expect to get a sound all that comparable to a real spring reverb, but it is in the same vein. The bottom line with the AIR Spring Reverb is that if you've got Pro Tools 8 you should absolutely check this one and the other ones out, as before you go out there and buy more expensive plug-ins for your system you should check out what is free and right under your noise to start!