"points are awarded to an applicant for experience gained in the 10 years preceding the date of the application"...this is correct meaning if you appled in july 2013, you can claim work experience gained from July 2003 to july 2013....
it is also true that CIC has to take into account "any years of experience that occur between application and assessment" meaning say eventhough you applied in July 2013, your file was not asssessed until July 2014, then technically you can update/add work experience gained within this 1 year (july 2013 to july 2014) while your file was in processing...
regarding your second question, you have to find the best NOC code that corresponds with the work you are claiming...mind you, for each NOC code they have a list of job titles accepted under that NOC for example for NOC 4012 you can use any of the following
college laboratory assistant
college teaching assistant
demonstrator, laboratory – post-secondary teaching assistance
discussion group leader – post-secondary teaching assistant
graduate assistant – university
laboratory assistant, college
laboratory assistant, university
laboratory demonstrator – post-secondary teaching assistance
laboratory supervisor – post-secondary teaching assistant
marker – post-secondary teaching assistance
post-secondary research assistant
post-secondary teaching assistant
research assistant – post-secondary
research assistant, university
teaching assistant – post-secondary
teaching assistant – university
teaching assistant, college
teaching assistant, university
tutor – post-secondary teaching assistant
university laboratory assistant
university research assistant
university teaching assistant
Most of us have used RA-university /TA-uiversity for this NOC...similarly, you have to look at the NOC codes corresponding to your area (i'm not familiar with engineering NOC codes, so i can't really comment more on this!)
Now another key thing is when you chose an NOC code/NOC title make sure you have done atleast 75-100% of the duties mentioned in that category...the more the better....we can never say what they mean by substantuial number of job duties, but if there are 10 duties listed and you performed 7 or 8 of these , i'll say you are safe!..and i know that it's hard to have done exactly the duties CIC wants...but then you have no way out...it s CICs guidelines for assessing work experience