The manual is confusing - I was not able to figure it out how it worked by the manual only too.
I wrote that to Zoom but the manual was finished already when I started to beta test the R24.
The R24 can do a lot of new tricks.
Here some facts:
1) There are the - well known - drum patterns - this time without any bass.
2) There are NO songs (of drums & bass) anymore
3) No option to change the drum samples
4) No option to change the single drum instruments (e.g. pan, volume for snaredrum only, reverb for single instruments, ...)
5) But wait - we have other options for my points 2..4, as well as there is no need for virtual tracks anymore - since we have unlimited wave files assignable to any track (since the R16)
6) The drums consist of two banks:
bank1 are labeled on the trigger pads, bank2 are optional instruments (percussion...)
7) While the old songs where for drums and bass only is the new 'track sequencer' for much more. It can trigger drum patterns and wave files in any combination.

Yes the track sequencer can be used to trigger single instruments (like your favorite crash sample) as well as complete drum pattern, audio loops, parts of your audio files ...
9) So in case you just like the old 'song' feature - than create say 5 pattern - assign them to 10 tracks (stereo) and trigger them (step by step - or in real time) to create a track sequence.
So now we know while we need 24 'tracks' - if you like to create a song with 12 different (stereo) drum patterns - then you have to use all 24 tracks only for the drums.
Of course you can bounce all this stuff later to create a stereo master drum (audio) track if you like and have 22 tracks for audio again.
10) My upcoming R24PatternEditor will allow you to create drum patterns on your PC as well as import patterns from you existing PS02, PS04, MRS, HD8, HD16 Zoom files as well as from Midi files.
11) Audio can be used in the same way as drum patterns in the R24.
That means you can trigger all kinds of audio stuff in combination with the drum patterns from the track sequencer.
12) These audio events can be played once (single shot) or in a loop for some times or endlessly.
13) These audio loops are unlike in other Zoom recorders seamless - no sound gap - and can be synchronized perfectly to your beat.
Example:
-Convert some midi patterns to R24 patterns with my PatternEditor
(or use one of the hundreds of factory ones)
-Store one guide pattern (e.g. 4 measures long) on track 7/8
(set it up to play endlessly in a loop)
-Record you bass guitar track riff on track1 - e.g. a 12 bar blues riff
(there are nice inbuilt bass guitar effects in the R24)
-Swap this track to track 6
(set it it to loop)
-Record you backing guitar track riff on track1 - e.g. a 24 bar blues riff
(there are nice inbuilt guitar effects in the R24)
-Swap this track to track 5
(set it it to loop)
-Now when you play this then you hear the drums looping all 4 measures, the bass guitar each 12 measures and the guitar riff each 24 measures - without the need to use the track sequencer - it's totally easy.
-Record the lead guitar on track1
-Record your vocals on other tracks
Your first blues record is done.
Now it's time to select different beats (intros, fills, endings) and change your rhythm - if you like.
Or you can create complete small parts for (intro, verse, chorus, solo, ending) and combile this blocks (drums and/or audio) with the track sequencer.
There are so many options !