My comment is for corrections only to the PDF:
1) AlSalat Alwusta is Not a noun, it is an adjective. Thus it can still be understood as 2 Salat by name.
(2:238 can be interpreted as to mean all your salats (i.e in your lifetime, hence the word is multiple plural. Also the end of the verse states to stand reverently = i.e in all your Salats = again lifetime)
2) Another interpretation to the "additional prayer" is that the additional refers to studying the Quran, not an additional prayer.
The command is to study the Quran at dawn, and then it states to also, during the night 17:78-9
(Compare the word additional which is also feminine here, but solely means additional, not an additional prayer 21:72)
That was my take on it. Verification is encouraged and commanded.