are there any builing codes for building a wooden porch on the front of your house?

Get the codes for your town for easement requirements. Other then that if you have an existing structure and you "fix" it or refurbish it there shouldn't be an issue. But to play is safe check the code. Many towns..If you are doing front work will want to see a permit. The fine for not having the permit can be quite steep.

Anything that involves an exit, like your front door, will require a permit. If the tie wall is for retaining soil slip, that's a permit as well. Since the porch must be anchored to the structure, you'd be better off getting that done first so the new siding will protect the joint.

In my area, a simple porch wouldn't need inspected, but I'd still have to apply for a building permit.

I can't guarantee you're area is the same.

Yup!