Thanks, Buddy!!It's simple:
1 In work history section, only include work experience for which you are claiming points. So, if you have enough points without current employment, don't include it there, and include it only in personal history. In that case, no need for reference letter.
2.Is this reference letter used to prove a work experience for which you are claiming points? If yes, then it's better to add in LOE how many hours you worked, and what's the legal work hours for full-time in your country. If you can, maybe add paytubs, as they often include the number of hours worked. If you're not using this employment in work history section, no need to provide any document related to it.
3.Same as (2)
4.You are correct. For spouse, foreign work experience doesn't get you any points. Answer "No" to the question, and mention all work experience in personal history only.
5.Provide proof of sale of shares with all your POF documents. For that, you can write a section specific LOE, which would be the first page of the pdf for POF. Provide any document related to those shares. You need to show it's not a loan.