RE: my phone memory full fast
You have very few options left with you as you have finished your device's storage capacity. Firstly I would recommend you to move all installed applications to the micro SD card. You should change the default installation of applications to your SD card if your Android phone installs applications directly to the phone memory.
You may expand your micro SD card by buying a new one. You must delete useless applications and stuffs from your phone to free up your storage memory.