On a Mac, it's Option+n (to get the tilde) and then n or N to place the letter.
Option+e gives you the accent mark and then the next letter you type goes under that accent.
On my phone (which I don't use for DL, but do use to communicate with workers who don't read English), I have to load a Spanish virtual keyboard to get the appropriate diacritical marks. Once you know how, this only takes a second.
Except if you address him as "Señor", then you have to use the formal, 2nd person or necesita. And it would be "el Señor" if you were speaking to a third party; or if you were speaking to the man in question you wouldn't put Señor in between the verb and the adverb. Eventually we will learn to hear these distinctions and we won't have to listen five times.