First and foremost. DO NOT USE code obfuscation. It is just worthless.
1) You can detected obfuscated code easily, its looks like a mass of random letters and number and other things. Detecting what obfuscating algorithm requires reversing the de-obfuscated function.
2) Depends on how it was obfuscated, is some cases yes in others no.
In either case. Do not bother.