New to the Android OS with questions...

[anken32]

I have my Nexus7 (Jellybean) for a couple of days now and love it.
 Have learned a lot with the help of this great forum.
Have downloaded "Lookout" to hopefully stay ahead of any viruses, etc. . Also, have downloaded "Kingsof Office", which is amazing.

Now I'm wondering if I need some kind of "Defrag". If I uninstall and application, do I just drag it to the trash? 
Before shutting the Nexus down, do I have to check (if so...how?) if any app. is still running. Is there a way to keep the OS optimized?
Again, I appreciate your advice very much!

[JayJ]

When uninstalling an application go to it's App info screen and Wipe data, this should clear any files that are no longer needed plus this clears the apps cache.
Android is not like Windows in the way it uses RAM, you do no need free RAM to open applications because the system will utilize RAM from another running application and close that application when RAM is need from a user request so it isn't necessary to stop or kill running applications.

[anken32]

Thank you JayJ, for the info.