Turkeys are very social. Getting him some turkey hens will be helpful.
My turkeys roost outside in all kinds of weather. Turkeys are very cold hardy. Mine have had no issues in -30°F temperatures.
All flock feed is fine. Layer feed for a tom, just like for roosters can shorten their life expectancy due to the excess calcium causing kidney problems.
What you read about low protein feed for longer life expectancy applies to broad breasted turkeys, not heritage turkeys. Mine do fine on a 20% protein all flock feed but can do well on feeds as low as 16% protein. The higher levels of lysine, methionine and niacin in all flock feeds is beneficial.
Adding a turkey will be beneficial for the tom and will cause less potential chicken problems than will happen if he tries to breed the chickens. The ideal addition would be a couple of turkey hens that have not been raised with chickens.
Gout is caused by excessive protein, mealworms etc. Excessive calcium causes kidney damage.