Panther, I wouldn't call the Spirit's line about "What's your story Mortlock? We haven't read the synopsis of the preceding installments." breaking the fourth wall. It doesn't imply an awareness on the character's part that he himself is appearing in a fictional story. Why would that make you assume he's referring to a Spirit story? Serialized stories were common in those days, and so were the synopses of preceding installments -- but Spirit stories rarely ever used that format, because the stories needed to read as self-contained units, even where there was some continuity with previous weeks' episodes -- so there were no synopses. I think they finally used them near the end in the "Moon" stories, because that was definitely out of the Spirit's usual milieu, and if you missed a week or two, you'd have been lost wondering what was going on. Normal Spirit stories featuring continuing plot-lines with Silk Satin or someone would just pick up in media res. Here the line of dialogue is clearly intended as the kind of hard-boiled, flippant snappy banter you read in crime stories, with an off-the-cuff reference to serialized fiction stories of any type, but probably specifically crime fiction. Nothing odd there -- the Spirit exists in a world where serialized fictional crime stories exist, too. He could have just asked, "What's your story, Mortlock?" without getting smart-alecky about it and adding the sarcasm, but I guess Wellman was trying to get cute, and make the Spirit look like a tough, cynical type.
The rest of your criticisms are right on the money, though. I suspect that Wellman, an experienced pulp fiction writer who probably was new to comic scripting at this point, was having some trouble tailoring his stories for the unfamiliar (to him) format, dialing his material in for the audience, and learning what to put in and leave out -- and he clearly didn't think certain aspects of the story through for logical consistency. Or, he didn't think much of the medium itself, and like you say, was "phoning it in". On the other hand, I'm willing to give him the benefit of the doubt. While I don't think much of it as a story, it had to be hard going from writing pulp fiction where you had tens of thousands of words to weave your magic, to as few words as would fit into an 8-page comic story. Conciseness while retaining ALL the essential information and making logical sense isn't always as easy as it might look when you're looking at an old pro's script for the same number of pages.
My suspicions of the artwork not really being that of Lou Fine might be either because it's really not him at all, or because it was Lou Fine trying not to be himself, reining in his individual talent and strengths, and "toning himself down", to blend in with whatever he perceived to be "the established Spirit style".