MN 1 questions (1)

Hello,

I've read through MN 1 and would like some explanations, if anyone is willing.

1) sabbadhammamūlapariyāyaṃ - is the last word of the compound pariyāya ( order ) or another word? If it is pariyāya, how does it fit into the compound? It translates as "the root of all things", so pariyāya ( or maybe something else ) seems superfluous?

2) ariyānaṃ adassāvī ( who has no regard for noble ones ) - what exactly does adassāvī mean ?

3) pathaviṃ pathavito ( earth as earth ) - I do not understand pathavito, what kind of ending is "to", I do not see anything similar in my grammar notes or in pathavi declension in the DPR ? Also in another instance - pathavito maññati - it is translated differently - "he conceives [himself apart] from earth" - so in the first instance the "to" ending is translated as "as" and in the second one as "from" ?

4) pathaviṃ mā maññi - he should not conceive [himself as] earth - would you say that "he should not" is the correct translation here? Because elsewhere in the sutta it is either maññati or na maññati ( does perceive / does not perceive ), and because of that I do not know how mā maññi should be translated?

5) vītarāgattā - what is the meaning of ttā at the end? DPR says vītarāga is passionless, but what is the ending ttā for? Is it atta as in self, soul ?

6) sammāsambuddha - what does "sam" mean? Perfect? I know sammā is rightly and buddha is enlightened. What would be the literal translation?

7) What is the difference between pariññātaṃ and pariññātantaṃ ? In the sutta it is "pariññātaṃ tassā" and  "pariññātantaṃ tathāgatassā"