When you buy a modded valve body it is a bolt in swap. Don't forget though you have to remove the pan and the fluid will also come out.
Some guys are getting away from the Edge Juice but not everybody. I have had mine for 3 years now and like it a lot. Some people do consider the Edge Juice to be a "beginner" box. There are other boxes like Bully Dog, Smarty, and TST which can provide more power and more tuneability than a Juice can out of the box. Keep in mind though, the Juice, with all of its gauges, safety backdowns, and adjustability on the fly, is one of the most well rounded boxes you can buy. There is a thread on here somewhere where a poll was taken to see what boxes people are running and last I checked, the Edge had the most users.
Believe me when I tell you that with a modded valvebody and an Edge JwA you will knock a couple seconds off your 0 - 60 time. I did it in 7.0 seconds with the Juice on 4.
Then I built my tranny, turned the Juice to 5, turned the MP-8 all the way up, and did it in 4.7.