What is legal and illegal when it comes to starting a stay at home business?

[ty]

Just now starting a business that will ,at least at first, will be based at my home. Im branching out into video making such as parties, weddings, people kid's hig school games to make highlight videos, advertisng videos for smaller companies. I have gotten some attention on my facebook business page now I want to know what I can and can't do.

First off a business license? Is this necessary for a business that is based in the home? What are the advantages to having a business license? Am I not allowed to have a business without one? I thought I heard that the primary reason for one would be if you are getting a loan a bank will require you to get one before they will consider the loan. Is that the only reason? Can I advertise without one? and if I need one what do they cost?

The next thing I want to know about is advertsing? I plan on making many advertising videos as a service to other smaller companies and also for my business as well? Am I allowed to use other songs in these advertisement? I have always heard about these copyright laws about how you can't use other people ideas and stuff if it will get money off of it, is this true for commercials? They will just be in the background to set the rhythm of the video. I will also be purchasing every song on ITunes they will NOT be illegally downloaded or anything so does that give me the right to use them for advertsing?

Thanks in advance for all the response and advice you all have for me. Its greatly appreciated
to bcnu: So your telling me every thousands of videos on youtube could be sued for $150,000 cause that basically the same thing id be doing. I mean people buy itune music and edit them into there videos on youtube and since you said they could be sued even if they don't make any money off of them that probably like 100's of thousands of videos that are illegal so something tells me that's not completely accurate. Im sure most if not all of those people who made those videos don't those licenses
So bcnu you are telling me that all those youtube videos we see of people making videos with music on them are all illegaly made. Since you said even if they don't make a dime they can be sued for 150,000 a song and im sure those 100's of thousand of people who buy songs off iTunes to edit into their videos don't have ASCAP o BMI licenes? Cause that's basically what id be doing? id never say the songs were mine or anything I would credit the artist. That all just doesn't seem accurate to me
ok sorry I just sent about the same thing twice. I sent it once and when the page reloaded and it didn't show it on here so I thought there was an error and I had to type it all over again so I had to try and remember and retype it and now I cant figure out how to delete one of them lol