How do I make my custom zombie more like a vanilla zombie?

I variant of a zombie for the mod I'm making but it doesn't work quite like a regular zombie. It looks like a retextured zombie with some different stats, but some of the functionality isn't working how I want it to.

For one thing, when I tried to apply the texture I made on the Bipedal model, it got all screwed up. So now I have a 'custom model' using block bench that seems to be the same. As is, it moves more like a player or skeleton, with its arms down to its sides, whereas I want its arms to move like you'd expect of a vanilla zombie.

Second, while I labelled it as undead it still doesn't burn in the daylight, he just kinda chills there with no issue.

Third, I don't know how to give it interactions with villagers like a vanilla one does. As is, it can do the basics like walking around, looking around, or attacking the player if detected, but I have no clue how to make it do the other zombie interactions with villagers.