Re: Music writting software
I use noteflight.com, everything is done in your browser, though the free membership is limited in terms of voices. You can pay the premium for $49/year and get more voices and better sounding instruments.
I like it because you can share notation to anyone you wish, there's a youtube sync feature which is really cool and as mentioned, it's all done in your browser!
There is also musescore and musedit that are free programs, not the greatest but it works.