- Can I use 2 AA batteries in the Wii remote instead of the rechargeable battery?
Absolutely. Any brand of AA batteries will do. Just as long as they are the same brand and not old ones. But to save money, I suggest you use one remote with a rechargeable battery pack and the other hooked to a charger until the other remote battery runs low and you can simply switch 'em.
- How to use an AA battery as a replacement for LR44?
Those 4 LR44 batteries are most likely connected in series. That means you need a 6 volt battery to power the unit. You need to replace 4 LR44 with 4 AA cells.
- Is there any 12 Volt battery that is the same size as a AA battery?
There aren't any off the shelf batteries the exact size of an AA but 12 volts. There would be too much risk of people putting them in things which were designed for AA's. You can't make the same size, consumer could confuse itself are ´burn' circuits. Every model needs to be unique.