2. If not opened email, send the email again in two days and then go through the rest of the sequence
3. Branch sequence depending upon task / call outcome
There are ways to pull all of this some of this with several sequences, workflows, etc. but it's not for the faint of heart and it's more than imperfect in functionality as well.
I have a very similar issue. I have a sequence where I someone opens an email I want it to set me a task to contact that person. At present this is not possible in Sequences. In addition, I would like the capability for a deal owner to have the system send an SMS to them to tell them if something has or has not happened.
I would support and +1 this idea as a great feature for email sequences. I'd love to add a task for LinkedIn outreach when someone engages with an email.