Not sure where in MD you are located, but Windows on Washington may serve your area. Great guy, and he sells "installed" or DIY. On product, for wood the big 3 makers are all pretty decent. (although I only like the Designer series in Pella). Some people like that screen, others don't. I installed one for my parents several years ago, and the bug thing is overblown by competitors with the interior screen. If you want bang for the buck, vinyl can't be beat. They'll generally offer superior performance numbers as well. My favorite is the okna/Himark offering, with a .26 u value, and .06 air infiltration rating. The latter is unheard of as sliding doors go. Sunrise and Softlite have nice offerings as well.

Check the size of your existing glass inserts to see if they are a match to replacement Patio glass inserts.

Draw in a to scale dining room table with chairs. I think that will make you want to move the patio door as you are asking about so you can more easily get out the doors and people can be at the table and with the doors still accessible. While I love the idea of hidden entry to your pantry, same comment as above. It seems a table and chairs will block entry. You can still make a "hidden door" from the hallway. I imagine pantry goods being accessed at all times for snacks or when having people over. So you do not want the person sitting at the table to have to move to access the pantry. Maybe my sense of scale is off and there is enough space. Try drawing in your table with the chairs to get a more clear sense of whether the table and chairs are in the way or not. :)

Yes the water is draining inside (not on the floors) I think maybe I need to replace the pile weatherstrip at the interlock of the two bottom panels. Or maybe add some caulking outside the patio frame. I would really like to know where the tiny insects are coming from. Thanks