there are some newer extensions that replace older extensions.
For example, if you have CSS Form Builder 2 installed, you will not need to install Universal Email 4.
CSS Form Builder 2 has UE 4 built into it, so replaces UE4.
from your description, it sounds like you had CSS Form Builder 2 installed, then installed UE 4 which broke Dreamweaver.
I dont know how far back your extensions go, but some older extensions like Photo Assist have been discontinued, and have not been updated for CS5.5.
As far as order goes, for the most part, there is not an order, except for the following extensions, these should be installed last in this order:
CSS Form builder 2.0.3 Support Update 2
Security Assist 2
If you are unsure of whether some of the extensions you own are incompatible or replaced with others, send a list of the extensions you have, including version numbers, and I will let you know.