You sample the past anyway. 
You can playback “imediately” the current SRC3 recording with microtiming, otherwise you play the previous recording…
Change original sampled track pitch to check if it’s in realtime.
If you sample ABCD inputs with SRC3 off, you don’t need microtiming.
In depth answers to these questions are covered in the video I linked here:
Seriously, @defenestration has put the work in here. It is the definitive reference as far as i’m concerned.
Yes, really good. It misses the use of 2 recorders though, which allows you to pitch up / reverse even more freely. 
Yes! Also opens up the door for infinite remixing (as you know!); pattern 1 remixes rec1 MAIN recording while rec2 recording; pattern 2 remixes rec2 while recording rec1. Can slice the buffers when not recording and use prepared patterns. A lot of fun as long as you can keep track!
1 pattern may suffice…
Destructive looping with Octatrack - #45 by sezare56
2 recorders can be also alternated, finishing recordings and stop, so that recordings can be mangled freely.
Example :
Recorder 1 records 8 steps from step 1
Track 1 plays rec 1 from step 9
Recorder 2 records 8 steps from step 9
Track 1 plays rec 2 from step 1
(use a sample lock)
Recorders can be alterned more oftenly, so that mangling delay is shortened…