My thoughts on each of the questions.
1.) No guarantees that google links do actually get checked or count for much. Recommendation would be to still include them, however, you should also include a snapshot/screenshot of what is in the google link.
2.) If it was actually part of the commercial requirements of the job (i.e. you were getting paid to train or the training is part of what is required for the company to use a particular product or service), then I am not too sure it would count for much. So for instance, if you are working with a cloud service provider and you have to train a cohort of clients about how to switch to the cloud, then this wouldn’t really count as contribution to the advancement of the ecosystem/industry.
3.) Yes you absolutely can. Combining screenshots/snapshots with excerpts and links for full details is a way to quickly get your point across to your case assessor.
4.) There is no rule on this. Seen people with different styles of articulating their evidences, including those those with and without summaries.