Custom Music = I've Got Problems

In an episode I'm working on, I'm using a good deal of custom music. The custom tracks seem to have problems however. :\'(

First off, all of the custom tracks have 0.5 to 1.5 seconds silence before actually starting. This is incredibly jarring seeing as all the music tracks that come with the game begin as soon as the level or level section has started. And because the custom music tracks have the silence at the beginning, it makes the player confused as to why the music hasn't started until it actually does. Because of that, it breaks immersion or something like that.
I was wondering if anybody knew how to fix this.

And secondly, which despite not being a problem with every track is more annoying, some of the custom music is just way too low in volume compared to the SFX. This means to hear the music at a decent volume you're going to have to increase the volume by a lot, which will just make the SFX way too loud. Of the two problems, I would really like to know how to fix this one, please!

Thanks in advance.

Send them to me via PM and I can send them through Adobe Soundbooth and MP3Tag, to reduce their file size and edit the tracks so to increase the volume without cranking the speakers and make them start when the level starts.