Also, t levels don't seem to clearly correlate with decreased or increased lifespans. And as your last link points out, lower levels of t (ie hypogonadism) are correlated with increased risk of CVD mortality.

Yes, you're right about that. The paper says that:

"Our meta-analysis shows that patients with CVD have, on average, lower testosterone level than healthy controls."

However, the paper also says that:

"Taken together, these results suggest that low testosterone may be considered as a marker of poor general health status, negatively affecting prognosis, rather than a specific CV risk factor (11, 84–86, 95). Low testosterone level has also been associated with an increased mortality in patients affected by non-CVD..."

In fact, since there is a tradeoff between health and reproductive ability, we might expect the development of health problems in previously healthy males to cause testosterone levels to drop, as a means of offsetting some of the negative effects of said health problem. This could account for why lower levels of testosterone are correlated with increased CVD mortality.

However,

Whether male eunuchs actually live longer is controversial to say the least.

is a statement which I emphatically disagree with.