Hello everyone, first post so please be nice!

I'm currently looking at upgrading to a database and separated server for my growing business. We've outgrown our simple way and it's no longer efficient so a change must happen. I'm very new to this and what to seek as much help as possible and do as much research as I can, by doing so I hope I can take it on myself. I want the design to be able to grow with me so I'm open to installing something that I may not currently need. From reading, I think a Relational Database suits my needs best but I get a little lost with the server and software required for what I want.

Requirements as follows...

More advanced features, search facilities (customers, orders)
Needs to be an easy and reliable way of tracking information.
I'd like to be able to run reports to know when stock levels are low (daily)
Easily able to check stock levels
Print invoices
Print reports
Create search queries based on specific information
System must be able to grow as staff increase and business grows = Multi-user database system.

Would like the warehouse staff to see the orders on the system
A standard form that tallies up with everything on the database, allowing all the information at the first attempt
Handy if Jane could get in touch with other people within the business (IM for example)
Standard order forms on the website including all data required to get the order correct at the first attempt. Must tally up with what is in the database
Daily backup, automatically
Security = Log in screen, password access, server locked away
Wants to be able to select where things are printed off
Would like to be able to maintain the database myself

I don't want to save information as an Invoice, would rather pull information from the database and print it as an invoice.

Guys, I'd really appreciate any help you can offer!