ability to trigger on specific day and time.
You can do this now. When you select a specific time trigger right below the time there is a slider that says use date.
No, you can't, not in Basic Rule.
For now, you would have to use Rule Machine to do this. It can trigger on a specific day(s) of the week at a specific time, or on a specific date at a specific time.
Sorry, didn't notice the tag