Dynamic Org-capture Templates

[Eric Thomas <eric@ericthomas.net>]

Does anyone know how to approach creating dynamic Org-capture
templates? I'm looking for IDO/Helm type of completion after a
template has been selected. If string does not exist, it is created
and added to future completions, similar to new files in emacs.

Example:

C-c c
"a" (activity)
Activity: math               (<--need completion here)
Topic: multiplication       (<--need completion here)
Date: 2017-09-11           (<--need default to todays date)
Start time: 07:00 AM      (<--need to define AM/PM easily)
Duration: 20                   (<--easier way to capture time?)
Unit: mins

And

C-c c
"a" (activity)
Activity: physical education (<--again, completion starts as "ph.." is typed)
Type: Yoga                         (<--completion)
Class: Level 2 flow              (<--completion)
Date: 2017-09-11                 (<--date picker of some kind)
Start time: 07:00 AM           (<--define AM/PM easily)
Duration: 90                        (<--easy method for capturing time)
Unit: mins


Maybe Org-capture templates are not the correct way to approach this?
Any direction is appreciated.

Thanks