They work very well. Most have working front planes, but it's optional. They're about four feet in length.
Conversion kits wise, there are two I know of on the market. Big Dave's conversion set- http://www.frontiernet.net/~bwelch/
Although the website says this conversion kit isn't presently available.
We also have the Caswell kit. This is very comprehensive with pretty much everything you need to convert the Revell kit.http://www.sub-driver.com/models/submar ... arine.html
The fittings kit is available separately if you want to mix and match, or perhaps grow your own dive system.