Primary noc selection

Seeking expert’s opinion, please help! I have already done my ECA and IELTS. My calculated CRS score is 474 (FSW). Now, I am planning to open my express entry account. My work history is given below:
a. NOC 4163 - 5 months - Full Time
b. NOC 6221 - 11 months - Full Time
c. NOC 6221 - 7 months - Full Time
d. NOC 1241 - 3 months - Full Time
e. NOC 4164 - Part time - 25 hours per week - more than 2 years - I am currently working there ( Primary NOC).
Now my question is:

  1. Can I choose (e) NOC 4164 as my primary NOC as my cumulative working hour is 2600+ which is more than the eligibility threshold 1560 hours?
  2. Will it be a problem if my primary NOC is part time?
  3. For my CRS score, can I claim points for cumulative NOCs ,(all the NOCs combined )?
  4. Can I claim points for 3 years of work experience in this current scenario?
    Would be really grateful if anyone can help. Thanks in advance.