This FAQ was taken directly off the R4DS website on (01/10/2007)
Q: Is the R4 Compatible with the Rumble Pack or Opera Ram Expansion?
A: Yes
Q: Will you support DS Homebrew Roms?
A: Yes
Q: What is the Battery Life?
A: Same as the Original carts, the R4 core components are chosen to maximize battery life.
Q: What about reading Speeds from the DS? Are they Equal to an original cart?
A: Original carts have various speeds, our hardware is designed to match the speed as close as possible. No problems to this date.
Q: Does Drag and Drop functionality work on a Mac and other Operating systems except Windows?
A: Of course Our device is fully mass storage spec compliant, and should work with any operating system which supports this standard
Q: Do I have to use patches and extra software to load files on the NDS?
A: Absolutely not.
Q: Will I need any other extra software or hardware to manage the R4?
A: Absolutely not.
Q: What colors are available from the R4 Adapter?
A: We are currently manufacturing White cart for first batch stock, we might consider other colors soon.
Q: Do I have to flash my DS firmware in order to operate the R4?
A: Nope! No firmware hacks or any nasty tricks are required to use the R4. If you change your firmware you lose your warranty!
Q: What languages does the R4 OS support?
A: English, Chinese and Japaness at present.
Q: Does it work on both DS and DS Lite?
A: Yes, every revision out and to come
Q: Are there any regional issues?
A: No, R4 works on every DS and DS Lite from around the world.
Q: How many files can I have on the R4?
A: R4 Adapter supports 128MB~4GB TF(MicroSD) card , 4GB=32Gbit. TRANSFLASH = NON HIGH CAPACITY. THIS PRODUCT WILL NOT WORK WITH 4GB + MICROSD-HC CARDS
Q: Do I need a pass key device for the R4 to work or can I just put it in my DS?
A: Nothing is needed! Just place the R4 with the TF card into the NDS slot 1 and power-up your DS .
Q: Is the R4 OS/Firmware upgradable?
A: Yes! And the best part is that its DEAD EASY and SAFE to do it
Q: Is the OS skinnable?
A: Yes.