Double wall vent clearance

[Anthony]

I think I am correct that a double wall vent is class b, if it has a locking mechanism.

What is the minimum clearance to combustibles? I think I read 1inch in the mechanical code book.
Someone told me it was 2 inches.

I am preparing to take the Ky. Journeyman exam if you can help further are these statements true?

A gas furnace vent should rise 1/4" every 12"?

2-45° bends are allowed OR one 60°? or are they saying you can have 2 45's and a 60° bend?

Condensate drain fall 1/8" for every 12" or 1%?

Thanks for any help you can give me. I have been out ofthe field for awhile and am preparing for the fact that I may need it to fall back on.

[Jerry Peck - Codeman]

[Anthony]

Thanks! That was a great help! So 2-45's in addition to a 60 would be ok?

[Jerry Peck - Codeman]

[Anthony]

Why does the code call out gas vent and gas connector?
i.e. "effective area of the vent connector and the gas vent shall be not less than the area of the appliance draft hood outlet," are "connectors" simply elbows etc.?
I apologize for the stupid questions but some of the wording of codes are confusing.
Thanks for your help you've cleared up a lot of my doubting my own knowledge.

[Jerry Peck - Codeman]