You should be aware of the following points:
Once the publishing feature is activated the ‘Save site as a template‘ option will be unavailable below Site Action.
Deactivate publishing features will not show back the ‘Save site as a template‘ option.
You’ll not be able to ‘Save site as a template‘ by any means.
Any workaround on the internet to ‘Save site as ...
You don't need SharePoint Designer to accomplish this. Instead you add all of these tasks, issues, documents, status and calendar on a web part page, or a wiki page - whichever you prefer. But first things first:
In all site content (gear icon, site content) you add
an Activity list
a Custom list (which you can call Issues)
You already have a ...
For this there are multiple ways, one of the best approach is using CQWP which will display data from all the subsites.
May this question is already answered at Accessing data from lists in sub-sites at parent site level
Before moving forward have a look to this once.