@Jane-Doh
So wing-body lift includes both the lift of the wing and the part that is "in the fuselage"?
No. Wing-body is the term we use at my current (and indeed former) employer to mean the total lift of both wing and body, but excluding the tailplane contribution. Taill-off is commonly tested in wind tunnel development so it's useful to have a term for that condition. It therefore includes the TOTAL fuselage contribution.
What variables increase this benefit? I assume a fuselage that was flattened where the wing intersects it, had wing-body fairings to blend it together and/or it's intakes were flatter than deep (if they were in the wing-root) would have better overall wing-body lift?
Generally, wing/body interface design, at least in the commercial world, is concerned more to address drag than lift. If you need more lift its generally better to add more wing than to make the fuselage lift more - the fuselage is a poor lifting device. Obviously the fuselage does generate some lift, and you wouldn't want to throw it away, but it's not a design criteria usually.
@grity
Interesting pic, but be careful of assuming that the low pressure region is directly proportional to lift. The fuselage is relatively long chord, so a much lower pressure drop will, integrated over the longer "chord", create proportionately more lift. But, yes, the diagram of the SEP is over simplified - usually a fuselage degrades lift compared to the isolated wing.