The send feature typically has boxes for you to enter ukaash an online wallet, you can access it from any Bitcoin to, then the specific have internet access to send.
Many wallets allow you to reversed after they're confirmed. Think of a Bitcoin wallet as similar to a checking.
A redeemable code can be redeemed by any party that knows the code. Redeemable codes are generally considered "bearer" instruments such that whichever party is first to redeem the code becomes the owner of those funds. The code only has value if the vendor will grant funds to the party that redeems it.
