coding fields like incident number, date, caller, etc into work order nots as a client user

[EsmondB]

I am a non-admin user agent who enjoys coding, and I have been using my knowledge to enhance user experience using HTML editing in additional comments. 
Our leadership team wants us to perform repetitive tasks in work order notes, such as copying/pasting dates, callers, phone numbers, etc. I can create templates, and I am trying to figure out how to add dates, callers, incident numbers, etc without having to copy and paste that information into additional comments without having to do this for every incident. 
Note that javascript is turned off.
Any ideas?
I have tried using something like ${number} with [code] and outside of code and it does not work. 

[jcmings]

As another commenter mentioned, response templates are probably the best way to achieve what you're looking for. I'd see if you can get that enabled. I wasn't able to find any way to comment data in with ${variables}. And if you don't have the ability to write business rules, you'll have to do this manually for the time being.

[jcmings]

Best bet is either to use the OOTB activity stream (as pictured in Runjay's response) or you can create a business rule to automatically post fields when they change. For example, if assignment_group changes, your business rule could post something like the following. With a loop you can check between any field you wanted (instead of just assignment group).

current.work_notes = 'Old assignment group: ' + previous.assignment_group ', new assignment group: ' + current.assignment_group;