Type-in traffic and bulk domain parking questions.

I have a couple of questions, or rather requests for opinions.

#1) How large a percentage of the Overture score for a (single) word can you reasonably expect in type-ins per day for the word.com? 5%?

#2) How many type-ins a day do you feel is a prerequisite for a parked domain to be likely to make a turn-around on the registration/renewal fees? Optionally, with which parking services?

Of course there are many factors at play in both of these questions, but I am hoping we can determine some generalities.