Good luck! I would say that except for the CCD assembly with the focus lens (which you do not need really to touch after the first steps) there is not much to break. Of course, you may sacrifice the assembly if you use (too much) force or scratch the parts but otherwise it is just a puzzle to solve with patience (in both ways). Definitely nothing is behind any “snap”: All parts can be removed/installed with zero force as long as the “puzzle” is at the correct position.
The primary enemy (unless you are dissembling only for learning) is just the dust. So prepare yourself with a some kind of air blower (smaller than the one used in metal workshops). I used regular air duster spray bottles but even those needed to be used carefully so that parts do not fly away…
I already wrote notes about lens disassembly, those are on my personal site http://panuworld.net/misc/canon/ However, I have to admit that they are just text only and not the quality of your work here!
1) my “second try” is not yet even “three weeks” old, so I have no idea if I could really help in avoiding the problem. Also the best amount of “extra tape” on the cable is unknown: too much would most probably stress the cable at other location (or start to smear). In addition, if the replacement cable was really unused (opposite to full lens units on the market), then it will anyway take years to break in my camera use (which is probably enough extra life for this particular camera anyway).
2) definitely there are many different reasons for “Lens error” but based only my analysis of the lens mechanics and googling about the mid-2010s free-of-charge repairs of some Canon models, I would say that cracked diaphragm flex cable is definitely at least one probable cause for error.
My replacement lens assembly failed after 3 weeks, with the exactly same symptoms! But this is actually as expected because the root cause is the internal design of the lens assembly used on Powershot S100, S110 and S200, which will cause them to fail pretty much after a given number of power on/off cycles. (The repair part I used was definitely a used one; I do not expect unused lens units being on the market really anymore.)
Technically, it is typically the FPC (flex cable) of the diaphragm assembly that gets a sharp turn which cracks its conductors. So if you carefully open the lens assembly in a clean place, you can just replace the diaphragm unit with its cable and save plenty of money in spare part price. But most important, if you open the lens, you can also add some tape to stiffen the diaphragm cable to avoid sharp folds — it (may) increase the life-span of the cable and therefore opening the lens is worth of it instead of just replacing it.
On S200, which has very similar mechanics, it is just possible to turn the display carefully into 90-degree position after removing the bracket so that the screws can be accessed in the next step. The display and rear control panel does not need to be removed in that approach. Naturally you should be then very careful not to hang the display from its cable by keeping the camera bottom on the table.
Based similar mechanical structure of S200, I do not see any reason why the microphone assembly needs to be removed separately. Just lift it away together with the top case.
Based on Powershot S200, which is mostly similar, screws 5 and 6 (S200 possibly had only one down there) are not related to the lens assembly and does not need to removed at all in order release the lens assembly.
Tried finding out problem in Powershot S200 lens assembly (which mechanically similar to S100’s), and disassembled it completely two times without finding anything to fix there. It was just an unexpectedly started lens error (no shock or sand) which kept the lens fully extended. I could not pin-point the problem to any specific functionality (zoom, iris, focus, IS): everything looked like fully functional and clean. Tried also cleaning the photosensors telling the positions of the different mechanisms, but no luck. The only positive thing was that I was able reassemble the 3-D puzzle two times without changing the failure mode.
Opening the barrel anyway resulted in so much dust in there that continuing fixing it was anyway unfeasible. So I ended to buy a repair part from AliExpress, and it fixed the problem straight away. I saved the failed assembly: may be some day I have to replace some subcomponent in the lens (e.g. IS) for which I now have spares (hopefully not - a clean room would be needed for that)…