Dan,
When you get to timber spans, fractions of an inch in depth make big differences, with the change you mention the numbers get well within the safe zone. Again this is providing no deficiencies are in the area of the rafter/plate connection zone.
Typically a fascia would attach to the rafter tails ends, as a stringer so to speak tying all the tails together. If you are wanting the exposed tail look, they can be inserted between the rafters, however, care should be taken in attaching to compensate for tension stresses applied to both top and bottom chords of the members.
The additional horizontal members would run from rafter tail/fascia to the structure; supposing the overhang would project at an elevation somewhat below the plate, the bracing would need to run to a solid member such as a beam or post, depending upon your design. This bracing would not need to be done at each rafter to provide a lot of support, ends and equal spacing,or every bent would ensure your piece of mind. all of this would take place below the roofing.
AS far as locating the collar ties, I would place them as close to the bottom third of the rafter span in order to help the overhang, if a second floor is planned, keep the collar ties within the lower 2/3's of the rafter span; if you have no second floor and the truss is decorative, the collar tie can run just above the plates with a king pin to the ridge and queens to 1/2 span.
How is the weather there, we finally got some rain in this section, accompanied by some welcome cooler temps.
Eric
