Is it appropriate to get graphics from the company websites to insert into your project?

Not really. You should ask permission from the companies to use their graphics because they may have their company logos on to the graphics may be copyrighted and you could end up in court (in the worst case scenario). I recognise that data put on the website has entered the public domain, but you can't just copy it and try to claim it is your work. Normally, if you tell them what you are doing, say you are going to reference them and it doesn't put that company's' reputation at risk, they will normally agree. If however you are from a rival company or using the material to the detriment of that company, then you could soon run into big trouble.