It's possible to get your actual iPad screen and control it on your iPhone, but the iPad needs to be jailbroken. There's an always up to date guide of how to jailbreak at Lifehacker.
Once Cydia's been set up, tap Search and enter Veency. Choose the first option, then press Install and Confirm. When it's done, press Restart SpringBoard.
After the restart, unlock your iPad and go to Settings. A new section called “Extensions” will appear in the list on the left; tap Veency under it.
Turn on the Enabled switch if it isn't already, then enter a password in the box. If you don't enter a password, you will need to accept or decline every request to connect to your iPad.
Now connect both the iPhone and iPad to the same Wi-Fi network. This is important because your connection will be slow over 3G.
On the iPad, open the Wi-Fi settings and then the arrow next to your Wi-Fi. Write down the IP address.
Get your iPhone and download Mocha VNC from the App Store. Open it and set it up for your iPad's IP address and connect. Refer to its help page for more information.
The free version of Mocha VNC will let you type using the keyboard and tap the screen, but only the paid version will let you scroll up and down.
When you're done, press the menu button at the bottom of your iPhone's screen, followed by Disconnect. On your iPad, go back to Settings and turn Veency off. This will prevent anyone from using your iPad over VNC without you knowing, as well as save a bit of battery life.
Since PhotoStream doesn't work for videos, your best bet is probably a 3rd party app.
If you're worried about your pictures being stored on the Internet, you might want to try an app such as PhotoSync ($2) or Photo Transfer App ($3). The former seems like it uses your Bluetooth or Wi-Fi connection to transfer between the two devices rather than uploading the pictures to a webserver and then downloading them on the other device.
I believe that any 3rd party app that deals with photos will need to be granted access to location information. The app isn't necessarily using the location information, it's just that that information is embedded inside of pictures taken while location services was enabled. Therefore, since the app could potentially access your location info, it needs privileges to do so, even if it never ends up actually doing so.
Best Answer
Nope iPads can't run as iPhones. An iPhone app on iPad will run with compatibility mode (which is has not exactly the same behaviour as an iPhone). You'll have to test it either with a real iPhone or with the simulator.