Family Guy music can be found on iTunes. The have the complete release of the "Family Guy - Live in Vegas" CD. The intro theme can also be found on YouTube, but it can't be downloaded from there.
The cheats for Family Guy The Quest For Stuff can be downloaded at soulgaminghacks.com.
Walter Murphy & Ron Jones are the composers on Family Guy.
Find the nearest search engine and search the words... "Family Guy sheet music for the trumpet"
Google Family Guy Theme Sheet Music
'are you ready' song
Do a Google Search (Either Image or Regular) for Family Guy Sheet Music Cornet
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Internet
They don't appear to exist but just Google Family Guy Song Books and links to sheet music appear.
It's not named music, it's just music composed for the show.
An iTunes account will not cause you to get caught with illegally downloaded music.
There are several different music editing programs that can be downloaded online. One is called Audacity which is a music editor and recording program.