How much internal storage does the iPhone have? Can it be expanded? Does the iPhone have a MicroSD slot?

All iPhone models use internal flash memory that cannot be expanded.

The amount of storage is listed on the specs page for each model, but also are provided below:

A number of high-end phones from Motorola, Samsung, LG, HTC, Nokia and others have a MicroSD slot that makes it possible to inexpensively add more memory to the device, but the iPhone models do not have this capability.

For readers not familiar with the MicroSD standard, it is a tiny flash memory card -- "about the size of a fingernail" -- designed specifically for mobile phones to hold "music, movies, video clips, pictures, ring tones and more". For more information regarding the history of the standard, please refer to PhoneScoop.

Photo Credit: Kingston.

Does the iPhone support Bluetooth?

Yes. All iPhone models support Bluetooth although the functionality has been restricted somewhat. Version 3.0 of the iOS, called iPhone OS at the time, added substantially improved Bluetooth support including "peer to peer connectivity," support for accessories, and Internet tethering as well, although AT&T did not support Internet tethering in the US at the time the operating system was released.

Along with revised wireless data plans, AT&T started offering Internet tethering when the iPhone 4 was released on June 7, 2010, and offered it for earlier iPhone models, too. Version 4 of the iOS also added bluetooth keyboard support to the iPhone 4 and iPhone 3GS. The iPhone 4S and iPhone 5 models -- the iPhone 5 (GSM/LTE 4, 17/North America), iPhone 5 (CDMA/LTE, Sprint/Verizon/KDDI), and iPhone 5 (GSM/LTE 1, 3, 5/International) -- support a bluetooth keyboard as well.

Specifically, all iPhone models released prior to the iPhone 4S support Bluetooth 2.1+EDR whereas the iPhone 4S and iPhone 5 models support Bluetooth 4.0.

Can the iPhone use iPod accessories?

The iPhone has a standard USB-based iPod "dock connector" port on the bottom, so the majority of iPod accessories that are compatible with modern iPod models are compatible with the iPhone as well.