It is possible to transfer from your ii directly to your 3ds by pressing a > b > 1 and then holding 2 until a secret menu pops up.

(It's like a cheat code. :P)

Reference Video Link

From the Wii to the Wii U it is simple enough to transfer the mii over via the Wii U's mii channel, that is if you've already transferred your data over from your Wii. It's a direct option in the mii transfer options.

Now since you already have a 3ds first you can synchronize your accounts on the Wii U with your 3ds making your profile mii the same on both systems.

Note that if you have network ID setup on the 3ds you'll can sync the profiles in order to have your eShop balance and wish list shared on both systems. It also will sync your Club Nintendo accounts as well.

Linking Club Nintendo account steps

In general, no, neither the Wii nor the 3DS is aware of whether an update or patch is available. You have to pay attention to Nintendo news online to be informed.

That said, 3DS games with an online component may be able to tell if you're running an outdated version, and do something appropriately. For example, Mario Kart 7 will error-code you if you try to race online without updating to 1.1. This probably depends on server-side code so a Wii could feasibly do the same, though I don't think such a game exists.

If you're lucky, Nintendo may send out a message to all systems telling people about the bug and/or fix, like how they did for the Pokémon X/Y save location freeze bug.