What are PIPA and SOPA? Why should you oppose them?

You may have heard of PIPA and SOPA lately. Even though they are US Bills, their acceptance as law will affect everyone who uses the Internet. Here is a video that will help summarise the issue.
I think most of us agree that the musicians, artists, writers and everyone else who work to provide the music, film, books and many others that we consume should be rewarded for their efforts. However, this is not the contention between those who support and oppose these legislations. I personally oppose these legislations because of the following:

• The method of control it uses is simply to make it hard to recognise the domain name only. Those who know the IP number of the domain name (which is quite easy to get with many tools online that provide this conversion) can simply type the IP number of the domain name to get to the files they need to get to.
• It is worrisome that entire websites can be shutdown due to the action of one user. Websites like Facebook, Google, Wikipedia, Twitter, eBay and many others can be shut down because one user, clueless about copyright, uploads a picture of a flower they found on the Internet?
• I'm not too clear on this but it seems to me that the burden on website owners seems highly impractical. These bills seem to propose that you can only link to websites that do not have any material that infringes on someone else's copyright. Before you link to a site, are you seriously expected to have access to each of that website's files and inspect them to make sure that each of their files are complying with the copyright laws before you can link to it?
• These bills seem to increase the cost of doing business (legal and compliance costs) for everybody and that cost will eventually be passed on to the consumer in the end. Therefore, the end result would simply be higher costs for consumers and put in place a barrier to entry. It stops entrepreneurs and small business owners due to increased start up costs. All we will have again, is a world dominated by bigger and bigger companies, therefore reducing competition. The effect on Piracy will be likely to be minimal but everyone else will be worse off.
• We must also consider what would happen when other countries follow the US and eventually pass on similar laws. With so many examples of Governments abusing their power to repress freedom of thought, these type of laws will inevitably be used to censor the Internet. This would be tragic. We all want the Internet as a tool to find useful, relevant and accurate information.

For a while, it did seem that these two Bills were to become law, but after Internet citizens were educated about the issue and protested, their passing seem unlikely at this moment. It would be of no surprise however, if we see them resurface in some form or another. It is still important to remember our list of objections so we can ensure each item is addressed when new versions of similar legislations are introduced.