Pets are bonuses, just like weapons and abilities. Each time you level-up you have a chance to get a random bonus, which may turn out to be a pet at some stage.
What is Domo
You can not get Siri if you jailbreak a iphone 4. In order to get Siri you have to download the app.
Yes, the iPhone 4 can have iBooks, but you must download the iBooks app from the App Store first.
You should try iHealth. This app is currently available for the iPhone 4, iPhone 5, and the iPad3. https://itunes.apple.com/us/app/ihealth/id608852599?mt=8
Yes, there is an app for Skype.
Search it on the app store
There is an app in the Apple Store
Yes
Buy it in the App Store for $9.99
Yes I Use it every day it is my lock screen on my Mac and IPhone 4
You'll have to buy the facebook app for free in the app store or you can get on facebook in safari but an app is recommended.
There are many Emoji Apps in the App Store!