Hello,
I'm afraid I don't understand what you're asking. I'm not sure what you mean by keywords "for" a specific website. Are you looking to find keywords that will cause your ad to appear on the website you mentioned? Are you looking to find keywords that will help advertise the website you mentioned? I don't believe either of these are available via the AdWords API.
I'm also not sure what relationship you are looking for between keywords and specific dates and times.
The process you outlined, where you create a campaign, then ad groups within the campaign, and then keywords within the ad groups, is a valid workflow.
If you give me more information on what you're trying to accomplish, I will be glad to try to help clarify.
Regards,
Mike, AdWords API Team