MikeH

Answer: It's safe to assume that due to the treatments he received that gave him his super-powers, he also ages a bit more slowly compared to other people. At least that's the way I took it.

TedStixon

Answer: While he may not really look like it in the film, based on information dates given in the film, Rogers would be 106 at then end. While not a common age to live to, it's certainly obtainable as non-super enhanced people have lived past that age (122 years old being the verified record). Also, it should be noted, people don't "die of old age." Being old doesn't kill you, disease, illness or injuries do.

Bishop73

Answer: The Loki from the original timeline is dead, but the 2013 Loki that is imprisoned on Asgard is presumably alive and well, and the 2012 Loki that escaped with the Tesseract is alive and supposedly, this version of the character will be the focus of his own upcoming Disney+ series.

Phaneron ★

Answer: The Loki who escaped is in a different timeline, so he will not encounter the "main" versions of the characters. This version of Loki will appear in the new series.