Some quick thoughts to get you started maybe?
For 1. this would depend a little on your quoting and line item process in Hubspot. If you’re just tracking amounts, and the amounts aren’t rolling in from line items and then quotes you’re producing in Hubspot (though you could still do this if you are, it’d just be duplicative and possibly come out incorrect since its more manual), you can create additional deal fields like: Renewal MRR: $$$, and New MRR: $$$. When the deal reaches a certain stage or closes, you can prompt the rep to identify the dollar amounts and run a report that way. Or if you are spawning these deals off the original deal, you can create a workflow to drop the original deal amount into the renewal MRR field you created, and use a calculated field to place the rest in the “New MRR” field. We do something like this.
2.1 You could run a workflow that generates a task if a contact is created that lacks the identified key fields and assign it to the Rep to complete.
2.2 Your solution works. The other option is to potentially use Association Labels.