I can't say much about the Flashwave but honestly I would go with CyberSync by AlienBees.
AlienBees: Remote Controls, Wired and Wireless Remotes for your Flash Units
The flashware cost $189 for the transmitter and the receiver. The CyberSync cost $159.90 for the same kit. But if you want to add more receiver for each flash, the CyberSync cost $69.95 per receiver while the Flashware cost $139, about double the price of the CyberSync.
I bought the CyberSync kit from a member on this board as a part of a flash unit. So far its been working great. They are very reliable and anyone who owns them will say the same.
One of the thing that I like about it is that it uses AA battery, the same as your flash, they are made here in USA and most importantly they are %100 reliable.
I sound like a sales man for them but I really believe that the CyberSync is a better unit.
If you are really in a tight budget I would check out the RF-602 from Yongnuo. The RF-602 have gotten really good results online and is an improvement over their older model. I do not own them but thinking about buying a set for myself just to try out. I need to get another receiver for my Cybersync and it cost less for their kit then one CyberSync receiver!
For about $60 you get 1 transmitter and TWO receiver.
RF602 RF-602 for Canon 5D 5DII 50D 40D with 2 receivers - eBay (item 180393806234 end time Sep-05-09 10:52:00 PDT)
We have some users on this board that tried them out and gotten positive results from it.
https://www.pentaxforums.com/forums/camera-studio-accessories/69648-rf-602-wi...-triggers.html
I know its not much but many other on the strobist form said they did not have any problem with it.
Now to answer your question
1. After looking at flashwave's site it seem that FW2 has more range (about 260ft vs 65ft
), more channels (gives you less interferance), more ways of connecting your flash to it and a higher sync speed of 1/200 sec.
2. You need to buy ONE transmitter, this connects to your camera, it send the signal. You also need to buy a receiver for EACH flash you plan to power. You are looking at about $389 for one transmitter and 3 receiver from them.
3. Yes once you go with radio trigger you it does not matter what brand of flash you use because most likely you will be using them in manual.