#1
why are the 4th and 5th notes of key construction refered to as perfect and or diminished verses major or minor. thanks
#2
i guess its just a matter of definitions... the 5th note has no tonality(as in major or minor)
,and it is really consonant(typo?) therefore its called "perfect"
#3
^pretty much right as far as I know. I'd just like to add that the 4th is called perfect because it's an inverted 5th.
#4
because in both major and minor scales the 4th and 5th of the scale is the same notes.

ie in E major the 1,4,5 is E,A,B and in E minor the 1,4,5 is E, A,B

thats my assumption at least.
#5
They are considered "perfect" maybe because their frecuency ratio is the simpliest, and therefore the most "pleasant" sounding (consonant), and therefore the most "perfect" mathematically speaking.
Considering the octave and unison as well they are considered perfect, since the ratio of unison is 1:1, the octave 2:1, the fifth 3:2 and the fourth 5:4...

Anything beyond that ratios is not considered perfect because it is not "simple" and not as "pleasant" sounding, but the ratios that follow (32:27 for minor third, 81:64 for major third, 27:16 for major sixth, and 128:81 for minor sixth) are considered imperfect since they are the simplest that follow (with the exception of minor seventh 16:9 ratio and major second 9:8 ratio, but those are considered dissonant instead, can't remember why)