Hi,.. I will highly advise you to go through the GUIDE and CHECK LIST in detail, with pen and paper to take notes. This way you will understand the whole process and avoid mistakes in going through the process.
Here is some info.
1)How do I calculate my ielts score based on latest point test system in each module as in L,R,W,S module.

2)How many points does my husband get for his qualifications which is as below:
First 10th
ITI diploma of 2 years after 10th as regular study
After diploma he pursued 12th through correspondence and what would be his total education years counted for.I mean will it be 12 years or 13 years and how many points based on this?
I will calculate with 3.3)I have experience letter,appointment letter from my company when I worked between 2003 and 2005 with all jobs and duties specified as per NOC.Do I still need to get latest experience letter from this 6 years old employer?or same letter issued at that time will be sufficient?
I think the old one should suffice. You will need to add a Cover letter, Attach the contact details of your previous Boss/Company.
Also remmember 2 years will get you 17 points for Experience. 4)my current working experience is different from my noc field.do I still need reference letter from current employer with duties mentioned at this time since it's got nothing to do with getting points for PR or a plain letter about my work will also do?
Yes you should get the latest as well. This will help to show what you are doing.
5)what proof can I provide for my salary as I was being paid cash and have no record of that.no ITR's either.
Provide Salary Slips or Bank statement with Salary shown. If cash was the method, as in your case, get a letter from your employer that gives details of your salary and time period you worked etc.
* * YOU NEED TO PROVE THAT THE JOB WAS PAID.