Use iPhone adapter to charge Nintendo 3DS

The 3DS, unlike the Nintendo DS before it, is region-locked. There are 3 regions: North America, Japan and EU/Australia. So if you buy your 3DS in Australia, you'll need to purchase games from either the EU or Australia as well. Nintendo explained their reasoning in the following statement:

“Nintendo 3DS hardware is available in three versions: Japanese, American and European/Australian,” Nintendo told us in a statement.

“Nintendo has developed different versions of Nintendo 3DS hardware to take into account different languages, age rating requirements and parental control functionality as well as to ensure compliance with local laws in each region. Nintendo 3DS also offers network services specifically tailored for each region.”

It went on: “Additionally we want to ensure the best possible gaming experience for our users and there is the possibility that Nintendo 3DS software sold in one region will not function properly when running on Nintendo 3DS hardware sold in another.”

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Short Answers

1. Yes
2. Yes
3. No

A bit more detail

1. Since the 3DS doesn't have a whole lot of built in storage, some sort of flash cart is going to be necessary. This likely remains true even if there is, or comes to be some sort of lasting hack that would let you run homebrew from the SD card slot.

2. Most flash cartridges store the bulk of their data on an SD card(usually Micro nowadays) that you provide, thus practically requiring an SD card.

3. To the best of my knowledge, the business of flashing the DS itself is an old practice. Before the system had been so thoroughly hacked, flashing was one of the favorable options. Downsides included the fact that it would technically void your warranty(but wasn't really easy to detect). Basically, you could flash your DS, but all of the up-to-date carts will achieve the same end result without changing anything on the actual DS.