There is too much stuff to ask on the letter but make sure you are concerned only with the check marks. Those letters are generic letters for everybody and have many options (requirements) on them, but they say that pay attention on only checked options.
Anyway in my case they have checked marked on " pictures with names, did I consummate (Rukhsati) the marriage if not then when?, proof of my visits to Pakistan, and proof of communication with my wife in the form of telephone bills, emails, online chat.
I guess its enough to have an idea, what they mostly ask.
so don't worry about all the requirements on the letter just pay attention with the check mark.