Yes, I had a neighbour once who grew tamarillos and guavas. They are quite nice but I don't recall having them since or seeing them in shops very readily. Perhaps more of a home grown thing . . .? (I found the tamarillos a bit weird tasting.)
Yes, I have tried a big variety of them. Some have the pinkish centre and some are just white. They also come in a variety of shapes. Some a little elongated and some round. Love them with a small sprinkling of salt mixed with chilli powder! Guavas are introduced to school children early on in India. There is almost always a guava cart standing outside of schools during lunch break when as kids we sneaked out and bought cut up guavas with a sprinkling of salt & chilli powder yummm! Said to be very good for diabetics. Also full of Vitamin C.
In Australia we have the fejoa and the cherry guavas. I just love them.
Yes I've tried guava as well as guava jam. I sometimes eat it raw with salt. Guava, it seems, takes on different shapes, depending on where it grows. Guava in tropical countries have a rounder shape and they tend to be smaller in size.