Verb tense questions

Hello,

Many kind thanks in advance to whoever can answer which is the appropriate verb for the below sentence:

The delegation from China are seeing/see the chairman the following Monday.

In general, present continuous is used to show set future plans, and simple present is used for a time table (e.g. The train leaves at 3 p.m.). Is the above sentence a future plan or time table, as the answer will determine the appropriate verb tense.

Also, I see a lot of what appears to be misuse of the past perfect tense, or I am misinformed how to use it. My understanding is that it must only show sequence of past events. For example, "I had lived in Canada for six years when I met my future wife." However, I often see sentences such as, "I had hated carrots when I was a child." To me, this seems incorrect, as it doesn't show any sequence of past events. Am I correct?

Finally, in regard to past continuous tense, what would be correct in the following sentences:

In August, several customers complained about the salesman's ethics. They said he offered/was offering expensive gifts to clients and was taking/took them out to expensive restaurants.

I think simple past is best because past continous usually shows something was happening when it was interrupted by something else (e.g. Sales were increasing when suddenly they started to drop.). Am I correct?

Again, many kind thanks in advance for answering the aforementioned questions.

Best regards.