I am installing a new wood stove (EPA Cert.), have mechanical permit, etc.

And I have built my hearth pad (proper R-Value to code, etc.) and have
located my wood stove on the hearth pad to manufacturer's specs. (Proper
distance from walls, etc.) This is the *only* place the wood stove can go.
The chimney is stainless steel 6" inside diameter and 8" outside diameter.
I'm Using Selkirk - Metalbestos chimney parts.

So guess what? The metal chimney going straight up will go right smack dab
through a rafter (45 deg. roof slope - one of many 2 x 4's at 45 deg. angle
supporting roof.)

So I will need to cut the rafter....

Questions....

Can I cut the rafter, then add 2x 4's which transfer the support for that
rafter to neighboring rafters?

I read that there needs to be a 2 inch separation between wood and the
metal chimney. If I do this where the chimney pops up through the roof,
there will be a 2" air gap going from the attic to the vented roof jack
(flashing). I am concerned about insects getting into the vent, then making
a home in the attic. Can I place screen or something somewhere in this area
(to keep insects out)?