Hello Lone Wolf

Building this Amati U-boat kit also requires some basic engineering skills.
Although, I have NEVER built this kit before, but I do see your future problems in getting this kit put to togother correctly..?

As you say, this kit has no hull lines, the problem can be fix very easily.
Putting lines into the hull you will require some MARK-OUT gear used in the metal engineering trades. You will need a: 1 Right angle plate 2. Set square
3. 300 cm metal ruler 4. Scribing block. 5 Small Spirit Level & "G" Clamps This is the tip on how you can put a correct parallel waterlines into a model ship's hull on both sides including torpedo tubes (doors) lines or any other lines that may be needed.?

First place the hull onto a flat and true surface and against the Right Angle plate.
Place a ruler on the side of the hull and take a measurement on both sides of the hull to see if it is at 90*?. Also place a small Spirt Level on top to see if is standing "true",? This will help you in the setting-up stages..
Place small "g" clamps between the inner top part hull that is against the Right angle plate & clamp it tight at both ends of the plate so the hull does not move.
Next use the Scribing Block and measure the height needed to scribe a parallel waterline onto the hull then lock it tight. Start scribing at one end and marking off at the other end of the hull. Keep these setting & repeat for the other side of the hull to be marked out. Then you are done.! Beware, don't push to hard with the scribing block on the hull surface or you will damged the hull, just push lightly & slowly as you go.
In regards to decks gun & AA guns my best bet would be too look around at 1/35
scale TAMIYA military German kits. You may be able to salvage a gun using these kit(s) for parts to make up a naval deck or AA guns for your kit..?

Hope my tips will help you..?

Cheers Joe Brennan