What if i want to make bulk changes to the core elements used within a group of templates? For e.g. i would like to update a number of templates with a new logo and a revised T&C all in one go, including adding/deleting text or data fields in the templates?
>> create a group and then add one or more forms to that group
You can create folders with Title of your choice and then add forms within that folder . Also, you could copy forms from some other folder location to this new folder.
>> making identical changes to all the forms in that group simultaneously
You can not really make identical changes to all the forms 'simultaneously'. However, you could choose to create one form and copy-paste it at the same location so that it will create a new form with a new Title of your choice but the form itself will be same as the previous one. Again,  will help you achieve this.