Only one qualification can be awarded the full points for a recognised qualification - people usually choose their highest level recognised qualification and go with that one. Any extra qualifications
may be eligible for bonus points (as you claim yours is because you started studying before 25 July 2011).
For work experience, if you know you're not going to be able to get any evidence which will state the company you worked for AND the dates you worked to and from AND your job title, it's safer to leave the details out. An immigration officer is going to be looking for those 3 details on whatever evidence you provide and so to provide evidence that doesn't cover those 3 elements isn't likely to be accepted anyway, and would just cause delays in the processing of your application while this is cleared up and it's established thta the evidence doesn't meet the requirements for work experience evidence.
Having more than 160 points doesn't actually help in terms of an SMC application - the area that people most often fall down in when it comes to their application being assessed is the skilled employment points. So even if you had 200 points when you applied, if you aren't assessed as meeting the instructions for skilled employment, you lose 50+ points meaning you go under 160 points for your application anyway, meaning game over.