Hi ottunifi,
Unfortunately I can't help you with questions 1 or 3 but i have some ideas on question 2.
For question 2 if i understand you correctly you want to limit each port ex: (eth1) to 20mbit down and up correct?
If so you can you update the router to the newest version 1.9.0 if not done already.
Then head over to the qos tab and go to smart queue. In this tab you can add as many qos policys desired.
In this case its for ports 1-5 before you do add the speed values go ahead and do a speedtest at speedtest.net and add those values to each tab and hit apply now that all the ethernet ports have policys for both upload and download you should not get anymore speed than what values you placed.
Notice: Smart queue is in my opinion the easiet way to configure qos on this router whoever if you want to configure qos in more depth which this router does support greatly you can head over to the support page which contains many articles on how to configure many things for the router go to this link to get to the support page https://help.ubnt.com/hc/en-us/categories/200321064-EdgeMAX
Also note that smart queue will lower speeds because it creates an artificial buffer to be able to place more important packets first than others. For example say you put 20mbit on one port you make get 19 or even 18mbit thats normal.
Thanks hope this helped
Unfortunately I can't help you with questions 1 or 3 but i have some ideas on question 2.
For question 2 if i understand you correctly you want to limit each port ex: (eth1) to 20mbit down and up correct?
If so you can you update the router to the newest version 1.9.0 if not done already.
Then head over to the qos tab and go to smart queue. In this tab you can add as many qos policys desired.
In this case its for ports 1-5 before you do add the speed values go ahead and do a speedtest at speedtest.net and add those values to each tab and hit apply now that all the ethernet ports have policys for both upload and download you should not get anymore speed than what values you placed.
Notice: Smart queue is in my opinion the easiet way to configure qos on this router whoever if you want to configure qos in more depth which this router does support greatly you can head over to the support page which contains many articles on how to configure many things for the router go to this link to get to the support page https://help.ubnt.com/hc/en-us/categories/200321064-EdgeMAX
Also note that smart queue will lower speeds because it creates an artificial buffer to be able to place more important packets first than others. For example say you put 20mbit on one port you make get 19 or even 18mbit thats normal.
Thanks hope this helped