Witr and Nawaafil

Sunnat Salaah before zuhr

Q: I would like to ask concerning about the 4 raka'at sunnah before zuhr. I heard someone say that there should only be one salaam in the entire 4 raka'at. Then someone told me that there should be 2 salaams, now I'm confused. Which one is correct? or it depends on which madhhab I follow? Please elaborate.

Missed Sunnats for Fajr

Q: When I woke up for fajar and after I performed wudhu there were 3 minutes left for sunrise. I therefore performed only the 2 rakahs fardh fajar and did not offer the 2 rakah sunnah. Was I correct?

Should I offer the 2 rakahs sunnah later?

Tahiyyatul Musjid

Q: When entering my local masjid shortly before fard salat starts, some people avoid sitting down before the fard prayer. They say this is so that they will be able to include the intention of tahiyyatul masjid in their fard prayer (they say that according to their madhab which I think is Shafie, the opportunity of tahiyatul masjid disappears when you sit down). I know that the opportunity of tahiyatul masjid is not nullified for us Hanafis by sitting down, but is it still recommendable for us to stand together with the others (i.e. not sit) even if we are Hanafis, to be on the safe side and to avoid ikhtilaf? I mean just as our books of fiqh says that it is mustahabb for us to redo wudhu after having touched a person of the opposite gender in order to avoid ikhtilaf.