I think its good what you're trying to do here. I wonder though if those explanations you provide will help or hinder progress in our collective understanding of when and how to use the differing aspects of Bulgarian verbs.
For me at any rate, there is little of value in these technical labels "perfective" and "imperfective". They may speak volumes to philologists but I suggest that for mere mortals like us here in MyBg, they are not at all helpful in creating a mental image of the two forms of a Bulgarian verb.
For what its worth though, here is the explanation provided in the very first Bulgarian language book I bought, back in 1994 - "Teach Yourself Bulgarian", then in its first edition:
"In Bulgarian, an action can be seen from two different points of view, or aspects: either as incomplete and still going on, or as momentary and complete. We refer to [the former] as imperfective and [the latter] as perfective verbs. In fact, you can think of each verb as having a 'twin' with which it forms an 'aspectual pair', and when you come across a new verb you should try and [sic] learn it together with its twin."
Which is all very well and good, but try to remember 24 hours later, say, which form of a verb is the perfective and which form is the imperfective and there's every chance you'll get it back to front. Because we really don't think of verbs as being "incomplete", or "momentary" - let alone as "perfective" or "imperfective". Because, being native English speakers, we've never had to think in this way.
So, in English we say "I go to Sofia" (or more typically we use the verb "to be" and the present participle of the "doing" verb - ie, I am going to Sofia). But to express an intent to do this, the "action" verb doesn't change - "I intend to go to Sofia tomorrow". Or "At the moment I buy (am buying) apples" and "This afternoon I want to buy apples."
Ok, so its different in Bulgarian but, as I observed above, its not helpful to try to learn the "perfective" and the "imperfective" forms of Bulgarian verbs. Because these obtuse terms don't really tell us native-English-speaking foreigners which is which.
So, I've settled on thinking in terms of the "simple" form and the "da" form of the verb. Here's why -
The "simple" form (ie, the imperfective) - the form you'll normally see in the dictionaries: We use this to make a simple statement about what we're (or of course someone else) doing. Think of it as the answer you'd give if someone asks you what you're doing right now. So - "В момента аз купувам ябълки" (At the moment I'm buying apples).
The "da" form (ie, the perfective) - I call it this because this form of a Bulgarian verb must be preceded by да, the Bulgarian equivalent of "to", that little word we use to join two verbs (which I just did!). And the most common use we Bulgarian learners will make of the "da" form is when we want to express a present state of mind about a contemplated future action
. Take the verb "to pay" - in its simple form, its "плащам" (plashtam), so "В момента плащам
моята сметка" (At the moment I'm paying my bill). But the "da" form is "платя". So if we want to say, eg, "This afternoon I want to pay my bill", we have to say "Този следобед искам да платя
Now Phreddy, as you rightly point out, there are further refinements to the rule but my thinking is that if we can get our collective heads around this basic difference in usage of the two aspects of a Bulgarian verb, we'll be well on our collective way.
I'll pause here for breath - and any reactions to the above ramblings ...