One possible alternative for quickly setting up stock comments for common issues is discussed in the comments under the accepted answer here:
How best to use the review queue?
(where you can see many "standard" comments discussed)
This refers to the stackapps script described here:
I simply use the Firefox add-on there (I also use Chrome as a browser but I tend to do most of my CrossValidated work in Firefox so I only have it set up there).
You can set up several comments (including links) for each of questions and answers (and several other things but I ignore the rest). I have changed almost all the default question and answer comment slots.
I rarely use what I set up unchanged though; I paste in one that's close to what I want and edit the result (beware - the pasted autocomment obliterates anything you typed before it so paste first, add later)
It's easy to set up, and easy to use (see the link to the stackapps page which describes how to use it).
This would be a way of getting some of what you want to do more easily that would work if your feature request doesn't succeed.
One thing in particular to note is that it automatically figures out if you're talking to a new user and auto-inserts a welcome message before the pro-forma comment (which Welcome you can also customize, as far as I recall).
That should make it possible for you to set up a good approximation of what you want for the self-study comment and your usual welcome, each in their own slot, in such a way that if you were talking to a new user posting a self-study question, both parts would be put in together, by choosing your "self-study" comment from the list.
I'd also add that (since you make a lot of them and they're not of lasting value) you should consider deleting old comments of this kind (after a few days, say). See the discussion of this in comments by chl and whuber under the question here:
Are plain "Welcome to our site" comments too chatty?
(I've deleted some of yours that were at least a week old, but so far only ones where they contained only a welcome and a link to the tour)