Baffled by old age

[Juffos]

As far as I know, death magic reduces the chance to get disease by 30% per level. D4-magi thus should be immune to disease, but they will still eventually become useless because of feeblemind.

[Anaconda]

So, practical example: to decrease the chances of Klaus the Mason to get afflictions, one needs to take growth scale, improve his dead magic skill and upgrade him, if possible, to master nature magic too?

Does luck item help? How about luck scales and/or shamrock icon(s) in particular province?

Does the increase in magic skill need to be permanent or does booster items do the trick?

Is there other ways to get hero younger than the blood spell where a hero bathes in virgin blood?

Does healing help units with age afflictions, or does it work only for combat and incident wounds?