2. How to show the SIP keyboard in xna app?

This is not in the CTP, but will be in later builds: Guide.BeginShowKeyboardInput

3. Explain starting with April CTP Refresh, I can compile and debug my XNA game, but it does not show up in list of applications when I am not launching it on the debugger?

The games are installed in games hub, which you can't see in the currently slimmed image. Change the Genre attribute in the App element in WindowsPhoneManifest.xml from App.Games to NormalApp
<App xmlns="" ... RuntimeType="XNA" Version="1.0.0.0" Genre="NormalApp" >

4. Suppose when I deployed my XNA app to the xDE, the orientation is in portrait mode, but when I deploy it to a device, it's in landscape mode.?

The XNA Framework defaults to landscape mode for Windows Phone games, but XDE doesn't yet support XNA in landscape mode, so portrait mode is the only option there for now. You can set your orientation preferences by using GraphicsDeviceManager settings (SupportedOrientations, PreferredBackBufferHeight, PreferredBackBufferWidth, etc.

5. Tell me is it possible to use Custom Pixel Shader in XNA?

From Shawn Hargreaves blog For this release, there are no programmable shaders: “Instead of programmable shaders, we augmented the existing BasicEffect with four new configurable effects: SkinnedEffect, EnvironmentMapEffect, DualTextureEffect, and AlphaTestEffect. These are designed to run efficiently on the mobile GPU hardware, and I think do a good job of providing enough flexibility for developers to create awesome looking games, while also meeting our goals of being able to ship a robust and well tested product on schedule.”

6. Tell me are there canned MVVM "Data Behaviors" planned for WP7?

Not at this time. The behaviors have dependencies in Silverlight 4.

7. Suppose Have a very simple application that uses the APplicationBar. The app bar shows one menu item when in portrait. However as the second image shows the app bar displays now items in landscape mode. Is that by design or a bug?

Yes, it's a known problem in the emulator on machines that don't support the hardware accelerated graphics in the emulator. It works properly on devices and machines that do

8. Tell me is it possible to run two instances of emulator on the same machine. I am doing some networking app and need two emulators to test it?

You can not launch two instances from the Phone tools. You can launch a second instance from command line.
c:Program Files (x86)Microsoft XDE1.0XDE.exe" "C:Program Files (x86)Microsoft SDKsWindowsPhonev7.0EmulationImagesWM70C1.bin"

9. Suppose I have lost one of the application templates in Visual Studio 2010. It's available in the file system but not in Visual Studio… Any ideas?

Try running Devenv /setup.
Running devenv /installvstemplate might also work; but that is going to slow down overall VS performance. The /installvstemplate is a development only option that makes it easy for developer to test their templates. This shouldn't be used on end user machines. Devenv /setup does a lot of more processing and caching to speed up VS performance.

10. in the emulator, NetworkInterface.GetIsNetworkAvailable() always return false?

This is a known bug in MIX CTP and April refresh. Sorry! It will be addressed in next build

13. Tell me in my code the method marked by [OnDeserialized] is never called after deserialization. Is this a known issue?

The following conditions should be met for a valid OnDeserialized callback.

1. The accessibility of the method should be public. It can also be internal with InternalsVisibleTo provided to the System.Runtime.Serialization assembly.
2. Return type should be void.
3. There should be exactly one parameter which should be of the type StreamingContext.
4. There should be only one of the four callbacks provided on the method.

16. What happens to IsolatedStorage when app is uninstalled?

It gets deleted. Content saved to media libary is not deleted on Uninstall

17. How to manage my Isolated Storage quota?

You don't have to. There is no limit

18. How to deserialize JSON from a rest call?

Use DataContractJsonSerializer. it is in System.Servicemodel.Web

19. Tell me is SecureString supported in windows phone?

No. Securestring is not in Silverlight.

20. How to access the LiveId credentials a user has entered into the device?

In this release, the credentials are not available to third party apps. You will need to prompt the user for credentials and manage these within your app.

21. Suppose I am trying to receive toast notifications in emulator app. I got everything setup but notification does not show up in emulator at all?

Make sure you have a product / publisher name set in the manifest.
Open WindowsPhonepmanifest.xml, under Properties. Edit Publisher="" to Publisher="something". Redeploy.

24. Explain where is XmlDocument class?

Instead of XmlDocument, use XDocument from System.Xml.Linq.dll

26. Tell me is there a way to detect if application is idle?

No. You have to do that yourself. yourself (you could subscribe to ManipulationStarted on the root frame with handled=true and then use a simple timer).

27. How to identify a device or a user?

Use Microsoft.Phone.Info.UserExtendedProperties.GetValue(“ANID”) in Microsoft.Phone.Info.dll. This is not in the MIX build. How unique is this Id? It identifies the user; so you could have a user with two phones. This is persisted across reboots, but not across factory reset (unless you reconfigure for same user).

28. Explain does the web browser control share the IE cache?

No. Each app has its own wininet cache. The webbrowser control instances in your app will use that app's cache. The IE cache will be separate

30. Tell me is WCF supported in Windows Phone?

WCF is supported on WP7. When you look at the SL3 version of WCF, WP7 supports that except for the following:

► PollingDuplex support
► Runtime code generation support for ChannelFactory.CreateChannel APIs
► Astoria/Azure support

31. How to sniff network traffic from the emulator?

Netmon 3.4 (beta) defintitely works. Fiddler works too. If using fiddler, remember to switch it to either trap “non-browser” or “all” traffic and start fiddler before launching the emulator.

33. Tell me are there APIs to read RSS/ATOM feeds?

You could use System.ServiceModel.Syndication from the desktop since it dependencies are entirely present in CF

34. Suppose my site is down, and async calls are taking too long to timeout. How can I set a reasonable timeout?

Per MSDN docs, you should call Abort() on your request when you feel iti s appropriate timeout