Hi Danny,
They all hold true even if you are using ACS.
1. Can you clarify what an MTA node / MTA server is? MTA stands for Message Transfer Agent and is responsible for shooting out emails to the target audience.
2. For ACS, are the sending IPs already determined? Yes. If your instance is hosted with Adobe, you can reach out to support for more information.
4. Do you have any suggestions on how to clean up my database of profiles to remove spam trap addresses? Check for active addresses by seeing if they are interacting with your emails. Spam traps need to be determined with help from deliverability experts. It is a paid engagement.
5. Can you elaborate a bit more by what you mean "Send email in waves"? I know that when I send an email to hundreds of thousands of people from ACS, it does seem to send in waves already (e.g. even if I set the delivery time to 8am not everyone will receive it at 8am of course). There is no Waves feature in ACS
6. Is there a way to see the size of the email in ACS before sending? I sent a test message to myself in Outlook and saved it to see the size. Yes, that is the way currently possible in ACS. In ACC, if you preview it gives you the size but not in ACS
Regards,
Vipul