Hi everyone - this is being marked as Delivered because the first two functionalities (association of tasks & filter custom objects) are live! The third request for the order of custom objects has also been addressed in that they are now ordered based on their create date, the way default objects like contacts and companies are sorted. 
With that said, if you are still interested in more customizable options for how associated objects are sorted on a record, please upvote or leave feedback on either of these ideas:
1. Display order of associated objects in right-hand panel
2. Re-order deals on right sidebar of company page
Any updates to that feature that may arise would be shared on those posts specifically! Thank you for your understanding.