To read and add data you can just use Composer's Rest Server functionality. The exposed RESTfulm endpoint can be called from the datalayer of your application.
For the database, you can use SQL , however the choice of database depends on the kind of development environment you are using. If your data is not that big you can consider AWS RDS cloud databases.
You can store the location if your data on the blockchain. By defining an asset in the Composer CTO and giving it a String property with a location. You can use the playground codes examples for reading and writing autogenerated Asset Registry. Use RESTful endpoint to read and write the data.