I think you misunderstood me.
What I said is that when you type, for example, 'Notepad' in the typing box to launch a desired program, and you get, say, 35 results, using your suggestion could mean something like this: just as you stop typing, you see the program you want to launch is binded to the 'P' key, so you press it, but instead of launching the desired program, FARR adds the letter to the present string in the typing box, resulting that FARR is now searching for 'Notepadp'. This is because the focus is in the typing box, not on the results list.
Solutions? The one I said before it's an option, another one would be using what you said, pressing 'Alt+<Alphabet Key>' to launch the app without typing the <Alphabet Key> in the typing box, and finally, pressing <Tab> (this is how it works now) to focus the results list and then press 'P' to launch the desired app.
I hope it's clear now
