Thank you
can you explain better why i only need backup the phrase when 'everybody' in the internet says i must backup the entire database (private keys, etc etc) or i risk losing some funds? thank you in advance
Because breadwallet is an hierarchical deterministic(HD) wallet. Unlike normal wallets, HD wallets have extended private/public key. All the private/public keys are generated from that extended private/public key. So, you only have to backup your extended private key.
No, you don't have to. The image is talking about cold storage(paper wallets, probably). Assuming you understand how transaction works, you will have to mention an address to receive 'change'. When you spend from paper wallet manually -- if you forgot to add a change address, change will be used as fees resulting in loss of that Bitcoins. However, in these wallets, here, breadwallet, it will automatically choose a change address to receive change. Therefore, you don't need to worry about change and you only need to spend Bitcoins you want to spend.