I am an Digital Marketing Consultant. Making creative digital strategists to produce innovative and unique, data-driven campaigns about industry trends.
I am having 8 years of experience in Digital Marketing. Certified Google Adwords, Analytics, Google Tag Manager, Bing Ads.
Best way is to create product feed with the 8 products with Google shopping feed specification. Link it with merchant center and start the shopping ads.
I suggest to add more products if you want better results. 8 products does not give you much traction.
I recommend to use sub directory if you want to take the SEO advantage.
In sub domain, authority & link juice will not pass and Google treat every sub domain as a separate entity.
I hope this helps.
You can set the process for running Facebook campaigns for many clients.
There are few tools available which can be helpful to auto schedule your campaigns.