Simple short answer for
Your second question
Unlike artificial languages, almost in all cases the languages people speak have grown long before a grammar was settled.
As a matter of fact Arabic grammar was only defined and settled after the revelation of the qur'an and the first steps the qur'an and the copying of Moshafs have gone through. The qur'an predates the Arabic grammar by at least one century and the different high Arabic dialects or languages which were called Faseeh predated it with several centuries.
Nevertheless there are basically two opposite schools of grammar the school of Basra which is closer to Hijaz and its typical conservative linguistic influences and that of al-Kufa which is known for some singularities.
And due to several historical reasons the language in the middle east has developed in a different manner to that in north Africa and al-Anadolus which until today is a bit more conservative.
The modern Arabic is highly influenced by the originally -at least for the wide public- unknown qir'a of Hafs 'an 'Asim which includes high influence of ibn Mas'uds hudhali dialect because it is the only qira'a with a high use of hamza, which was not regarded as fasih nor as a letter by all other known fasih dialects. In fact there's a dispute about the amount of Arabic letters based on whether shiddah (which has low amount of supporters) is a letter or not and hamzah (which is regarded as a part of al-Alif) is a letter or not between 28, 29 or 30 letters.
The first question
A detailed answer in my humble opinion doesn't belong here, but as stated in the comments, analysis of verbs must start from the "Infinitiv" form which is the third person masculine singular in the past form. Anything else stated on Wikipedia actually can be true, but must not and it is only general statement and to be capable to distinguish different grammatical rules etc. one must practice the language and have a certain experience which cannot be built by simply reading rules or self-study -> external input and validation is certainly needed.
The verb: توفى is certainly neither of what you've mentioned in your analysis:
Now, in the Quran, 2:234 we see that the verb يُتَوَفَّوْنَ is used.
Based on that analysis from Wikipedia, this should denote emphasis or repetition or intensity or something that makes it different from the simple present verb.
In fact you missed to mention the only applicable option it is causative, as توفى means causing death.