Hello,
1- If the customize includes the addition of information not available on the dashboard then unfortunately it would not be possible. There are limited changes you can do in terms of customizing the dashboard like customizing your summary report.
2- You can with API calls
https://n216.meraki.com/o/3yCuOd/manage/support/api_docs/v1#list-the-uplink-status-of-every-meraki-m...
The only page close to that information on dashboard is Org overview but will not detail the connectivity per WAN
3- Similar to 2nd
only thing close to it is if you go to Org > overview > devices> select the devices by type > add the uplink 1 and 2 column and you can download the report. But it would not give the connectivity. However, you can explore API to get those information