Transistor Tremolo improvement

[Znake]

Hi all,
That's my first post, I'm quite a noob in building pedals, expecially mod effects.
I recently built a transistor tremolo (http://2.bp.blogspot.com/-mUYiVnvN7VE/T4R_O0EZ8wI/AAAAAAAABOI/haQ-88_lU0w/s1600/Monster+Effects+Swamp+Thang+-+smaller.png).
I like how it sounds and that there is no clock bleed, but now I would like to built a more versatile version in a 1590B box and extend its range of usability. The problem is that i don't quite understand enough this circuit to know where to mod!
Here's what I would like to do:

• Move the "fast" switch to a second footswitch
• Add a volume pot
• Add a waveshape pot/switch to obtain a choppier trem*, better for fast speeds

*If this can be done as a parallel connection could be also hooked to the second 3ptd footswitch (double speed only uses a row of pins) which would have 2 rows of pins free having the faster/choppier activated with 1 click.

Can anybody help me with the volume and waveshape mods?