why signing, unknown sources and how to sign

Hi!

I exported my processing sketch as a app. But are a bit confused with the signing

Heres what I did (and maybe tutorial for others):
1) In processing: File -> Export Android Project
2) In Eclipse: File -> New -> Android -> Android Project from Existing Code
3) select the project you exported from Processing (Root Directory) in the wizard
4) doubleclick AndroidManifest.xml in the Package Explorer and change android:debuggable="true" to android:debuggable="false"
5) mark the project in the Package Explorer
6) FIle -> Export -> Android -> Export Android Application
7) Create new Keystore and set location for export and choose password
8) enter the key creation
9) select the destination for the .apk and export

Now I have created a .apk file

My questions:
1) Is my app signed? And how do I know that?
2) Whats the point of signing? Is it possible to install without signing?
3) I need to tick the checkbox in my phone for allow Unknown Source to install?4) And since the answer is Yes for the above question. Do I have to do this even though the app is signed?

thanks

 

thanks!

where do I find jarsigner then? inside eclipse somewhere?

is there way to export and install an app (without putting it on the google play) so you dont need to have the Unknown Source checkbox checked?

 

okej. what do you mean?