There's a lot in this but here's the helicopter view.
Opening to a set form -- easy. Create the form first and save it. Then Tools | Startup, pick the form from the drop-down list and it should be the first thing the users see when the db is opened.
Buttons to show you stuff -- Create the queries or reports that you need. Then go to your main form in design view, drag a Command Button onto the form with the Wizards activated, and follow the prompts. You can make the buttons open forms, queries or reports, without having to write any of the code yourself.
VERY brief, but you asked to keep it simple... If you need help on the specifics, post back