The size chart is spot on to me. For jerseys, probably focus on the weight range if you have a gut, and on the chest measurement if you're thin. The fit guide tells you how each will feel within that size: relaxed will be loose, standard will have some room but not enough to flap around excessively, slim will be tight and not flap around, elite will be skin tight. I made the mistake of ordering a standard fit one size down to make it feel like a slim fit, but that turned out to be too short and rather tight in the gut while still loose in the arms. So probably best to just find a jersey in the fit you prefer. Bibs really only have one fit, although they do seem to have different inseams if that's a big concern for you.
That's apparently their second best chamois, at a price to compete with the off brand companies. I just couldn't bring myself to risk people striking up a conversation about an album I just couldn't grow to like.