If I have an older verion, could I mix it with MX04?

Let me start by saying how pleased I am by finding this cool site, I have been looking for a source like this for a long time. I am looking forward to make new cyber friends!

My question: I have an older version of Flash in one of my friends computer and I need to know if I could use files from that version with the newest Flash ( MX 2004) version?

Also I would like to hear your opinion in which is the easiest way to build websites. Do you only use Dream weaver files/actions or Do you build your website only with Flash? Any input I really appreciated.