بارك الله فيكم = Allah blessed you all = [baaraka allahu fihum].
we can say also "for one person" : بارك الله فيك = [baaraka allahu feek-a]
* we can use it to be pleasure about something done from someone. It's the same using of "god blessed you".
جزاك الله خيرا = Allah reward you the good 'things\wishes..' = [jazaaka allahu khayran]
/kh/= as /j/ in Spanish
we also can say "for lots of people": جزاكم الله خيرا = [jazaakum-u allah khayran].
* we use this one as "thank you".
for the answer of the first: we can say :
وإياكم
بارك الله فيَّ وفيكم
the second one we can say : العفو = [al-3afw] 3= ع
regards
Regard.