You will probably be running several different programs at once, so your machine will need a fair amount of processing power. If you're planning to host your site out of your home, you will need to investigate server options. Be fore-warned, this is an expensive undertaking. If something goes wrong, a reputable ISP will have your problem solved in no time. This will save you in terms of both money and headaches.
Some computers have an internal fax as well.
Your marketing costs will vary depending on your chosen methods. A lot of free marketing options are available on the web, in terms of content trade-offs between sites and tapping into different communities that might promote your site by word of mouth. If you are able to get a lot of sponsors and advertisers to commit to your site, then you will be able to make a profit. This all depends on the subject matter of your site and whether taking out ad space will be profitable for potential advertisers. Watch out for home business scams .