This is an A minor tune, the most used key in the musical world after C major.
The lead is some kind of brass instrument, a modified version of the trumpet patch. The bass line is a modified BASS4 default patch with some delay added (C4-E4 are the notes, if I recall correctly).
The drums are the clap patch and the default hi-hat. That's two, which leaves two additional channels for lead or bass inside the drum sequencer. Used one of them for a vibraphone (bell) secondary lead in some of the song's patterns.