Hello everyone... What is exact meaning of social smile?

1.My baby smile whilr playing, when some one hold her and talk to her sometime she smile sometine not..,

2.at night when i woke her up for feeding and put on my lap she smile ..so these are social smile.. She is completing 2 month on this 9..

3.And one question at while brestfeeding she put her eyes ball up ward and look at my face , i feed her lying..so is she making eye contact.. When anyone hold her she look for few min lik 1min then move her eye.. What it means

And

4. she pass some kind of sound like huu..aaa etc.. So she is

Plz help i m alone..and after reading somting on google darr lagta hai.. So is my baby started make eye contacf