a couple of pointers here if i may,
he doesnt speak english (actually he probably can speak 1 a few words as iv heard him joking around 2 times when using english words). But i doubt he will read letters. also speaking is different from reading.
He doesnt have english speaking khadims. I know that for a fact.
The address will be the generic one for Mazahir uloom, thats the one you need to write to. you need to include his name at the top though.
Invitation - If you dont know him and he doesnt know you he wont come, his travels are already limited to only a few countries in a year. He would consider requests only IF something is happening in your country i.e Bukhari khatam, Bukhari start, Darul uloom opening etc. It needs to come from an elder. You may need to keep requesting. I know that a specific country where he has close connections with have invited him on many ocassions, they even offered him permanent resident, but he declines.
Naseehah - He might say something like Salah etc, If not then he will definitely say read Maulana Thanvis malfoozat.
Feel free to write off to him though.
A student of his wrote down all the malfoozaat sheikh sahib uttered in hadith class and wrote them in a book.
when he presented that book hazrat said something like whats this, dont read this, read maulana thanvis malfoozaat.
a leading khalifa said about that book that its great, but he is a mountain of knowledge (hadith) so we should extract all that information from him.
his passion in life is hadith. If he is to come my personal opinion is that it would be more likely for hadith than tassawuf. But i am not his khadim or special attendant so better your elders ask him themselves.
In khatme Bukhari, sheikh sahib mentioned something about Hafidh ibn Hajar and how he used a quote from another scholar to add weight to the meezan hadith. He said after reading the whole book in where this quote is supposed to have been attributed to i couldnt see it.
Sheikh sahib says i told you this in 1 minute, it tooks hours of work on my part to get this knowledge.