For those who are new to beta, I've found a guide on the various rewards and achievements tip sheet

Does the part vs practice AI really work?

I played vs all normal AI using my priest deck but never got the 100 gold.

I can verify that I got 100 gold after leveling up all my classes though.

keep losing if using rogue
now change to mage, better a bit..

how u guys earn the coin?
at the bottom right there got 1 blue potion icon, what is that use for?

finally i got my keys this early morning after i whine in every hearthstone forum and fb page , gosh i'm so happy now   

The Coin only Generate to those who play as second player. about the blue potion part, I do not understand unless you can take SS and post it right up here ?

sorry, now is not a right time
u try to look at the option screen there (where u can choose, Play, train, arena), if im not mistaken la. it's smtg to do with the crafting i believe .

keep losing if using rogue
now change to mage, better a bit..

how u guys earn the coin?
at the bottom right there got 1 blue potion icon, what is that use for?

Rogues got nerf kau kau from last wipe/release, now the flavor of the OP month is priest decks. You can see all the QQ in HS forums.

now is beta mode, everything will reset back to original once official launch rite? except those cards we bought with cash?

There is no confirmation about resetting the whole thing after the first wipe, subject to change thou.

He's asking about official launch, which is yes, everything wipe and all packs bought during beta will be refunded in coins for repurchase when official hits.

No more wipes please... I'll QQ my Golden Ysera go poof 

now is beta mode, everything will reset back to original once official launch rite? except those cards we bought with cash?

All beta test cards will be removed when player collections are wiped during the closed beta testing process. But fear not! Players who made a purchase from the in-game store will receive a gold credit equivalent to their previous card pack and/or Arena purchases.

As a token of our thanks for helping us test the in-game store functionality, players purchasing one or more items through the in-game store will receive an exclusive Golden Legendary card for their collection.

http://us.battle.net/hearthstone/en/blog/1...oming-9-26-2013 [pooff!! gone with the wind]  

Will there be any wipes in the future?

We don’t anticipate any further wipes. This goes for both the Hearthstone beta and after the game’s official release. Any progress made during the beta after the wipe will be retained through the release of Hearthstone, such as new cards you obtain, levels that you gain and ranks you achieve. Basically, you’ll now be able to keep your stuff.

He's asking about official launch, which is yes, everything wipe and all packs bought during beta will be refunded in coins for repurchase when official hits.