Q:

Designed schema and loaded data -- is it possible to build an app that will just visualize this data from custom user requests? 

Quick question -- I'm new to salesforce but I tried to dig around and want to 1) check if my understanding is correct and 2) see if something is possible. 
Basically, I have a schema that I built using Salesforce and loaded in my data successfully using Data Loader. 
Now, I want to build a front-end app that will let a user query that pre-existing data and get information about it. 
So in a very simple sense, they might ask "how many of X things did this person order" and it'd just spit out a number. 
Or, they might ask, "what is the total number of units sold from these different vendors?"  in which case the readout could be a table or a bar-graph (this would be fancy and awesome, but I would like to learn how to display both for the sake of learning). 
Do I need to do this programmatically or is there a built in or pre-existing library/App I can use that anyone is aware of?  I kind of chose to play with Salesforce because 1) I wanted to learn it and 2) I thought I could get do this without having to code (I've done something similar already in Java where I coded it manually with a separate DB).  
Sorry if this is a stupid question -- I'd appreciate any advice.  Don't hesitate to let me know if anything is unclear! 

A:

This can be achieved by Reports and Dashboards in Salesforce without having to write code.  However, I won't be able to explain how to use reports and dashboards in this answer - it will simply be too long.  
You can go through this trailhead: https://trailhead.salesforce.com/en/module/reports_dashboards for how to use reports and dashboards in Salesforce.  
Since you already got the data from data loader, so I am guessing you understand how data is stored in Salesforce.  Then report and dashboard should be the way to go. 