I am deciding to download Ubuntu. I have a small question about its UI. When you type out an application name, do you need to click on one of the suggestions using your mouse? or can you just press enter to start the highlighted application? Is it possible to navigate through the suggested apps that match your query using your keyboard?
You can press enter if it's a single suggestion or use tab and/or the arrow keys to navigate through the suggestions and then press enter. No need to use the mouse.
You can also double-tap enter and it will automatically just launch the first result even if it hasn't yet displayed the result in the dash.
You can just type a character or two, then hit enter to launch the application. This will launch the first result. Keep typing if the application you want isn't the first one.
You can also use the arrows on the keyboard to select the next few results. Press the down arrow twice, then move right down the list.
Have a look over on YouTube to see some more about the Unity interface, it's the fastest way to see what it can do. Just type Ubuntu Unity in the search there, you will see tons of videos.
By the way the Unity Launcher is the panel with icons that lies against the left hand side of the screen. What are asking about is called the Dash. It is a large panel that appears when you click the Ubuntu icon at the top of the Launcher panel.
In the Dash you get a search panel where you can type the name of a program and then press enter and the program will load or if you only type a part of the program's name you get a choice of possible programs and you use the mouse to click the icon to load the program.
This link takes you to the 11.04 Help document that comes with Ubuntu
Ubuntu 11/04 Help Document
Regards.
You can also have a look at Kupfer, Synapse and Gnome Do. These three are keyboard friendly app 'finders'.
In the example shown here, I started by typing g, and it showed me gedit as an option. I then made it 'gi' and it showed gimp.
Each of the three applications mentioned above behave in different ways but the basic idea is the same - quickly finding documents and applications with your keyboard, pressing enter.