1= yeah it would be covered in the warranty
2=yes and no, the engine is the same but in 2010 minor changes were made (cant think of them all but were some changes ) , the turbo in the 2007-2009 had issues with turbos having bad seals
3=is kinda hard there are few diff things i have heard to try but dont know what works best(someone can chime in maybe on this)
4= mazda extended the warranty on the turbos on certain models that had known problems ie:bad turbo seals and cover it up until 70k miles , along with the vvt on some models covered with extended until 70k miles (the vvt on the mazdaspeed3 that were effected were from 2007-2010 )
if someone wants to correct anything i may have stated wrong go for it , i know the info on the turbo and vvt extended warranty because i use to own an 2007 mazdaspeed3 and got the letter for the extended warranty (but traded it in for an 2012 mazdaspeed3 )
