How can you change the range of view of monsters and the range from when they can do damage to a player in Minecraft 1.7.10?

I always wanted to have a certain mod that works to my taste. Unfortunately I can't program well with Java, so I relied on MCreator to create the basic setup. Until then, everything went well. Now I've looked in the code where everything is written, what MCreator has written. I wanted to ask where the parameters for the visibility of the mobs stand, so how far away can they perceive me? In a forum I read that the text should look like this, which is responsible for how far mobs are allowed to see: "EntityPlayer entityplayer = worldObj.getClosestPlayerToEntity (this, 16D); if (entityplayer! = Null && canEntityBeSeen (entityplayer))"

Can it be that by "import" the commands of other mobs on my mob was taken over and I can change them only with @override? If so, how should I change that?

And is it possible that this monster can beat me from 3 blocks away, how many players can do that?

I know I should try to understand the Java for a long time before I try to rewrite a mod myself, but I want to wait until my graduation, which is not far away.

Usually you get a quick answer, but I think, as far as Minecraft is concerned, nobody wants to deal with the stupid Java code LOL (understandable xD)