The way you are feeling is perfectly normal and I'm sure you will be a great dad.
General worrying is fine and it seems like you have a good grasp of what to expect.
Is having kids easy? No. Is it worth it? Yes. I wish I could tell you newborns were easy, but they weren't (for me anyway). They can't talk or move, they typically don't sleep for long periods of time, need to be fed or changed constantly. The good news is that they are adorable and you will hopefully enjoy them anyway (some parents actually prefer this stage the best).
I prefer the toddler phase better, when they start to develop, move, talk, and play.
Remember that it's OK to not be perfect, just be there for your family and try to enjoy the time. It's over a lot quicker than it seems.