One issue is that if you're at 375 lbs, they may be reluctant to recommend any particular bike for you. A while back, I was looking through the Cannondale catalog, and they recommend maximum weights for their bikes, and if I remember right, that was around 275 for the average frame.
On the spoke issue, I'd probably ride it until something happens. Generally, that'll be spokes breaking and the wheel going out of true. When that happens, consider having a new wheel built with increased spoke count. If you overload a wheel, how it performs will partly depend on how it's used, and not just the weight that's put on it. So I generally don't ride a bike off curbs, try to avoid potholes, etc. When I first started riding, I had a $100 mountain bike, and the two times I took it off road, I tore up a rear wheel. You wouldn't think bouncing over a pasture at walking speed would be that hard on a wheel, but it was.
On saddles, there can be multiple issues. Part of it may be you geting used to the saddle. I've not had much trouble finding saddles I could be comfortable on, but some people have a major challenge to come up with one, so don't be afraid to try something different, either.
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"be careful this rando stuff is addictive and dan's the 'pusher'."