Yes, and we recommend you complete them in order.
Yes, you can. You will notice there is no link for purchase for the certificate itself - you simply purchase each training individually by going to the certificate page, where all the courses are listed, and add them all at once to your cart. The benefit to doing it this way is that they will all be in your dashboard at the same time and you can progress through each one as needed.
You may also purchase them individually at different times - if you do this, we recommend that you complete them in the order they are listed on our site for that particular certificate.
Also, if you take the Foundational Programs for one certificate and there is overlap with Foundational Programs required for another certificate, those would be applicable towards a different certificate as well. Please note that you are responsible for tracking your program progress as well as which programs you still need as you work toward earning the Certificate.