Hola!
I am experienced Android developer and can deliver you an ultimate app which will fully satisfy you, no doubt!
I created apps related to all components you wanted to have in this application! Integrated Database, Weather apps, Alarms and Timers, Screen Savers based on image changing (with special effects), Battery apps, integrated File Managers. All what you wanted to have.
Also it will not be expensive for you. since the app you described are well-known to me I placed the the price near lowest border you offer.
I am almost always online and you will be able to see progress during the work. Daily update and friendly communication always. Also support after delivery is without any questions!
Let's discuss you project further! Your project really an amazing one and I will be happy to start asap, almost immediately.
With best regards,
Sargis Simonyan