The session menu takes you to session detail views for mixing down the session or configuring session options
Mix all the tracks together into a single new stereo track. Mixdown uses the same pan and gain options that you set on the main view, so "what you hear is what you get".
Loop / Crop / Trim
Select a section of the song to play or dub. This affects all the tracks including the rhythm track. You can also loop over the selection
Monitor and Countdown
Live monitoring lets you listen to yourself in your headphones while you lay down a new track. Countdown is the time delay from when you hit the record button to when the recording starts.
Set the exact file format that you want for any new recordings. Use this if you want to save space on your iPhone, or if you want better quality or need a specific file type for compatability with desktop applications.