As your plant goes through the flowering cycle, it will start to get more and more yellow. This is normal and you should not feed your plant a lot of Nitrogen during the budding cycle. It needs a little bit but it needs P and K more, as well as Mg. What have you been fertilizing with? Your leaves don't look too bad, how many weeks has it been flowering for? The closer you get to harvest, the more yellow the leaves will get.
Some will start to turn brown and fall off, mostly the older fan leaves. This is normal also and you should not cut them off until they fall off on their own or come off with VERY gentle pulling from you. As it buds more, the plant will not look perfectly healthy like it does in your pic 1 but that is normal as it uses up energy inside itself in order to make bigger buds! Depending on how long it has been flowering for, that plant looks pretty good to me!