I do have a series of .jpgs that upload to dreamhost every few minutes, and a set of 2 very small weatherflash CSV files that are "post"ed to an API, one of which is updated once per second and the other once a minute.
I also have comcast. The problem with comcast is they won't tell you how much bandwidth you have used monthly, they just tell you that you have a cap, and they only tell you that if you ask. Googling you will learn that customers get peeved when Comcast throttles them because they had no idea they were near any threshold, or that they didn't in fact have unlimited service. Comcast also seems to selectively enforce as well. I personally have never been throttled, and 250GB is alot of data, but have friends that have been and they seem to think their usage pattern has never really changed, but Comcast just decided to enforce to pull a chain.
I don't know how to tell you to calculate the monthly bandwidth for a video stream to the server. The jpg are easy tho, take the average size times the number that would be uploaded per day, add say 10% for some overhead, and multiply by 30 days.
Yes you can in fact add port forwarding on your router so that someone could just navigate to the camera via browser. (that option doesn't involve using dreamhost hosting, you might however want to add and A record to your domains DNS to point back to the camera, something like camera.domain.com. If something else is listening on port 80 at your IP address tho then you will have to move the camera to another port, and that will have to be specified as part of the URL (i.e. camera.domain.com:8080 or 8081 are common alternates.
The other method involves setting the camera up to "Push" the video or still images to the server at dreamhost. With this option you will be using you comcast upsteam bandwidth 24/7/365 whether anyone is "viewing" the site or not.
Also I don't know if he has that specific need but the guy over at saratoga-weather.org has a set of scripts that are available for download (he accepts donations, if you solve a problem with his stuff and/or make it part of your site don't forget to remember him ) He has scripts for the most common weather station needs, since that would be a common need there may be one there for sequencing some weather cam pics.