help - measuring conga/ bogo heads

[tomtom]

Hey everybody, I am new to this website and from the looks of it I have been missing some good stuff. My problem is the following and I need help.
1. I have a set of traditional Toca Congas and Bongos and I ordered some Remo fyberskin 3 heads for the Congas. The Quinto head was too large but the Conga head fit. I don't know if I am measuring right. Where do I measure from/ to?

2. When tuning, what is the best way to tune so I get the best ring when I play? I sometimes get one to ring but the other seems flat or vise versa. The fyberskin 3 seems to tune however I want but not the natural skins. One of the best ways I have found is to tune every second lug then tune the lugs I missed. Can anyone give me some pointers.