Leaderboards/High Scores/Push Notices

This is a bit of a multi part question trying to see what will work best for me.
I’m at the stage where the game is complete and all thats left is implement is some high score systems and facebook integration.

I have looked at a few plugins but not sure which way to go. I notice that there are a few that are platform specific (android kit, ios kit) and some that are php based.
I would like to have a single high score board that takes all platforms and I would then like to have this displayed on a games website, so guess that would be the php based ones. They do lack security though. If I were to use a platform specific one, is there a way to display that feed on my site?

When a user gets a score then, generally how will they enter their names? Would it be better to store the user based on a login at the start (they pick a name) or can the info be retrieved via android/iOS specific functions? or use their facebook credentials? With that way the scores could be pushed to facebook too.

In terms of updates, do I need to implement that within the games code? Or when I publish a new version to the app store/google play, does it (gamecenter/google play) automatically let the user know there is a new version available to download?

I have been looking at Stans Asset packs:

Does anyone have experience with them?

Thanks for your insights.
Cheers

Ive used Facebook for single highscores…

PROS:
works on both mobile platforms + web
dont need to know serverside stuff
Score system is available out of the box (FB unity sdk package)
Meaning, you dont need to config the server side of things
U can grab their FB names / details / display pic easily
FB sharing features

CONS:
Requires FB login to use…doesnt work if user doesnt log in.
Can only store one score variable… cant store multiple scores variables…
Therefore need database for multi scores…

I stayed away from GameCenter because i saw it was easily hackable, and every game had hacked scores
However, Apple says the new IOS 8 coming out will fix that…

Hope that helps