Immortality

*spoiler alert!* || *spoiler alert!* (drag to see)

In the 3rd act of the main quest chain, you will get a 3rd option where you bring both ulfric and tullius with greybeards moderating, to a peace treaty. It really does pay to be neutral, since the stormcloak and imperial camps will always be something you can drag a dragon or a giant to help out on.

/*spoiler alert*

Smithing - I'd go with heavy, not to wear heavy armor, but to upgrade daedric bow with. Because to get 100 heavy armor to get the perk you're describing means getting hit literally over several thousand times. That's the only way to improve armor. As a sneak based path, your objective should be to avoid getting hit. But this is skyrim, so I guess go wild on being the silent, metal clad, ranger.

Tickle your spoiler thing is just temporary... You still either do stormcloaks or legion.

Stalyx, the perk from heavy armor doesn't make you less likely to be detected though. So even with that perk you will be less likely to be detected in light armor.