Pesach Questions

Question

Dear Rabbi, Sorry to bring up pesach so early. Just a few questions about preparation before the 'rush': 1) What is the exact (practical) definition of libun gamur, and when does it need to be used? 2) What, if anything, is the definition of libun kal and when, if ever, should it be used? 3) What is the measure of kezayit in modern terms? Revi'it? 4) If food was taken with a ladel out of a keli rishon and then poured onto a plate, is this iruy keli rishon? 5) What if you're not sure about the main use of a keli? Is it a safek drabannan lhakel? 6) Is there any lechatchila preference to kasher keilim that are mainly used as kli sheini in kli sheini water that is yad soledet bo like the shulchan aruch seems to suggest, or is it OK even lechatchila to use them without any hechsher (I assume washing with cold water is obviously a must)? 7) Which of these is correct: a)The rule of rov tashmish only pertains to kashering a keli, which is derabannan. However, if you put a spoon into hot milk and then five minutes later into hot meat and there is less than shishim, then, regardless of how you generally use the keli, it is a problem OR b) Even in the de'orayta case it is OK because the 'kashering' is automatic, so to speak? 8) When you steam up a pot with the lid on, does this also kasher the lid, or do you need to do hagalah on it separately? Thank you for your help. Sorry about the extensive list!