Could you please help me out with second point OR point me to someone who can.
For example, after creating sandbox account for user, I might wish to send Outbound/Inbound call notification to that user. So what APIs to hit in that case and what would be complete flow for the same.
We don’t offer any API endpoints for direct outbound/inbound call notifications (you can log calls as Activities), but what other CTIs have done is to use a Chrome extension to manage this part of the telephony integration. You can take a look at some of the current offers here: https://marketplace.pipedrive.com/apps/phone-solutions
What about pop ups. Will pop ups be shown in consequence of logging an activity OR I have to use other APIs for that OR (altogether a different question) does pipe drive provide pop us facility?
Yes, that’s correct, you would be posting activities on both Outbound and Inbound
Pipedrive doesn’t provide a popup feature itself, you will instead need to create this feature via the Chrome extension (which unfortunately I’m unable to provide guidance on).