Don't store your bitcoin with coinbase. Exchanges can seize your coins, be hacked, etc. You may not receive both coins in the case of a fork (bitcoin + altcoin, e.g. bitcoin cash or segwit2x) or you may receive the altcoin instead of bitcoin.
You can use exchanges to buy bitcoins. However, it is more secure to store your bitcoins in a wallet that you control, e.g. electrum for desktop, mycelium for mobile, blockchain.info web wallet, ledger hardware wallet, or a paper wallet. Unless you control the private keys, you don't fully own the coins.
I don't know about free bitcoin apps. However, there are bitcoin faucets that give away small amounts of satoshi (currently 1 satoshi = $0.000043). You can find a list of bitcoin faucets here:
http://bitcoinrotator.in/Is coinbase the best one? What are the legit alternatives of coinbase to buy BTC, ETH?
With good rates and fees of course.
You can buy bitcoin with cash, gift card, bank transfer via localbitcoins.com, paxful.com or find a bitcoin ATM with coinatmradar.com. You can convert BTC to ETH or other altcoins with shapeshift.io or changelly.com.
but why coinbase working too slow ?
im trying send my BTC to address my friends its always need 2 hours before payment recived :/
I don't use coinbase. Maybe the fee is too low. Bitcoin transactions with low fees may take hours to confirm. For quick confirmation, set a higher transaction fee. Check bitcoinfees.21.co for recommended transaction fees, or use this free transaction accelerator:
https://pool.viabtc.com/tools/txaccelerator/