I think you will need to have the screen door open in, because if it
opened out I *think" you need to have a landing area of something like
3' x 3' right in front of the door. The idea is that you aren't
standing on a stair and have to open a door toward you. You better
check the codes on that one, because I'm not certain about that.
Make sure they don't screw up the transition from the existing roof
onto the new roof. In my experience that is a common area to get
messed up in one way or another and you end up with a leak.
Make sure you are ok with the fact that there will be less light coming
in throught the set of windows that looks out onto the enclosed part.
I would kill to have a back porch with a roof at our house, however my
wife has ruled it out because it will shade the kitchen window and
reduce the amount of light coming into the kitchen window. Our's faces
north, so it's already the low light side of the house.
Personally, I would never use a "rental house carpenter" for anything.
I heard a story second hand about one of those type of guys who turned
a 400 sq. ft. deck into a room addition on the back of someone's house
for ~$6k. It turned out so bad that the owner is furious, but can't do
anything about it because he agreed to the plan before it was built.
Walls are sagging so bad that 3 out of 4 sliding doors no longer
operate, the roof leaks, there was so little insulation that the heat
bill went through the roof, etc, etc.