Now for part 2
. As far as I can think right now, whenever we have a legitimate "so [adjective] as to..." construction, our initial "so [adjective]" will be modifying some noun that precedes it, and then we'll have "as [linking verb in infinitive] [new adjective]." Since that linking verb will link that new adjective back to the preceding noun, the phrase will essentially mean "so [adj] that it is/was/appears/appeared/seems/seemed (etc.) [new adj.]."Some examples:
The dog was so dangerous as to be practically unapproachable. (so dangerous that it was...)
I hatched a plan so brilliant as to be nearly unfoilable. (so brilliant that it was...)
The sky was so bright as to appear fiery. (so bright that it appeared...)
He is a man so evil as to seem inhuman. (so evil that he seemed...)
