I believe the B-29s also landed nosewheel first. As do B-52s for that matter.
I’m sure others here can address that better than I can. If you’d like to get a firm authoritative answer, you could post over on the Warbird Information Exchange, as crew members of the CAF’s sole flying B-29 have been known to post there.

As far as the type commonality goes…
The B-29 was the base aircraft.
The Stratocruiser/C-97s (except for the three prototypes) took advantage of improvements to the 29 that came about for the post-war B-50 production.
Briefly the differences between the B-29 and B-50/C-97/Stratocruiser were: different engines (and the “chin” coolers), a taller vertical stabilizer and redesigned structures with improved materials (with 75ST aluminum instead of 24ST..IIRC, I don’t have my book at hand).
The transports used the basic B-29 fuselage and wing carry through structure for the lower lobe of their “double bubble” or “figure 8” fuselage structure.
The tankers were the KC-97s with fuel tanks in the main fuselage. To give you an idea of the commonality between the types, later in their lives, some KC-97s were retrofitted with the auxillary jets removed from tanker modifications of B-50s, the KB-50s. It was a straighforward procedure by all accounts.

The Guppies were rebuilt and stretched C-97s or civil Straocruisers with enlarged fuselages…some also had turbine power. How their flying characteristics differed from stock aircraft, I won’t guess.