The first issue is coming from the fact that you have lead module installed on the instance. This can be verified by checking the Home>monitoring tab and clicking on display beside installed packages. Please see attachment.
The third problem is coming because of the type of field. If you change the type to string from date you would see the full name being displayed . But for date type field it truncates to the first word. This could be a limitation of in SQL names for date type fields.
I am still checking about the 2nd problem and will let you know why that happens.
Packages can't be properly/easily uninstalled from Campaign. The best option here is to set a new and fresh instance and not install the lead package at all.
About your second problem, can you check if an element has the same name in the original schema? For instance, if there is already a "content" element in nms:deliveries, then this extension must have another name to be properly taken into account.