Hi in response to your points
1) Nope, unless you fail the completeness check, if you fail at any stage beyond that you will not get your documents back.
2) For any work experience to count either for the minimum 1 year's full-time employment in one of the 29 in-demand NOCs OR for the work experience contribution to your points matrix, detailed job descriptions must be provided including salary, length of service, hours worked and full job duties.
3) That's correct. The new forms I think are much better and less confusing. There is now just 1 single CIO checklist for everyone, and no visa office specific checklis.
4) Yes this is something which has changed this year. When we applied, my wife was PA but still I had to provide full references and contracts for my last 2 jobs, which was kinda pointless considering my employment history does not contribute to the points in our application at all!
Please note that it is very unlikely they will accept scanned documents - work references must be original. So if I were you I would try your very hardest to re-gather original documents. If that is absolutely impossible then send the copies and an explanation saying that the originals are with them, and hope they decide to match them up. Don't bank on it though.
Best of luck with your application,
Wayne.