Penfold-book sequencers

[Jeremy N Bradbeer]

I have just looked through the Penfold book and am thinking of rigging up the 
sequencers. The circuits look very simple (good thing) but I have a number of 
questions mainly relating to ganging or otherwise combining these circuits to 
get more sophisticated configurations.

So here goes:

1. Are the Penfold sequencers any good?
2. Do they have any inherent problems in their design and if so are there 
simple fixes?
3. Can switches be added (eg ahead of the diodes) in the note-sequencers to get 
rhythmic effects by omitting notes in the sequence?
4. Can the diodes be replaced with LEDs to display the sequence (like Doepfer 
etc) progression?
5. Can several note-sequencers be run from a single 555 to get different 
control voltages for e.g. filter parameters etc in addition to pitch and etc?
6. Can the percussion-sequencer and the note-sequencers be run from the same 
555 to get e.g. accents by using the voltages output by the note sequencer to 
alter e.g. filter/env. characteristics of the perc. sounds?
7. Can 2 or more sequencers, running at different tempi, be synced i.e. to 
produce polyrhythms etc?
8. Can the frequency of the 555 be voltage controllable - imagine the fun of 
having tempo controlled by an LFO or EG?
9. What would it take to convert the analogue voltage outputs into MIDI data to 
allow control of MIDI devices and to record into a standard MIDI sequencer 
(like the Doepfer sequencer does)?

Thanks for your input.

Jeremy