Yes, my TV has the composite video cable(yellow, red, white).
1. Do I need to hook this all up through the converter box(analog to digital) or do I bypass the converter box?
If the composite (Y/R/W) ports are not in use, then you can bypass the converter box.
2. If I use a wireless connector, do I need to have wireless service thought Verizon(I currently have DSL)?
"Wireless" cellphone service is NOT the same as 'wireless' networking - the Westell 6100 has router capabilities BUT NOT wireless functionality, so you will have to connect the Roku with an ethernet cable (like you are using to connect your computer)
3. I have a Westell 6100 modem - does that count as a router. Also, I looked on Verizon's website - it said
"Changing your Westell 6100 modem to Bridge Mode. In order to use third-party routers with your Westell 6100 modem, you must first change your Westell modem to bridge mode." Is this something I need to be concerned about?
The Westell 6100 is a DSL model with built-in router functions as well - you needn't bother with the 'bridge mode' (unless you decide to add an additional router)
4. If I don't have cable service will I still be able to access some of the free stuff Roku says you can receive such as music? It streams through the computer. Now I just realized I can't use my computer and watch movies on Netflix at the same time?
To do ANYTHING with the Roku you need INTERNET service (which you're getting from a DSL provider) - if your internet service comes from a cable provider you need to keep that service (but not any television cable offerings). You CAN watch streaming video via the Roku and use the computer at the same time IF you connect both to the Westell 6100 (see comments below)
5. Whether or not I have a Roku, my computer needs to be next to my TV in order to hook up the computer router to the TV, not the best situation space wise, but if that is what has to be done.
The TV is NOT connected to the Westell 6100 - only the computer and the Roku are. However, the Roku will need to be close to the TV for the video connections and to use the remote. Ethernet cables can be 25ft or more to connect the Roku to wherever the Westell 6100 is. The Westell has ONLY one ethernet port - so you will need a simple 5 port ethernet switch (~$15) (This will give you more ports to connect both the Roku and computer - a 'switch' is NOT a router!)
...the pros and cons to getting a Roku vs. Seagate Free Agent theatre vs. WD Live Plus HD media player. Are the latter two only useful if you have an HD tv, more expensive?
All these products, like the Roku, require connecting to the Internet via a router in order to stream internet video. The Seagate and WD devices are more geared to streaming video from a local harddrive (but there are ways to do that with a Roku as well.)