On the database settings dialog, you can configure various database-related settings.
On this tab page you can specify general things like the name of the database and a description. Additionally, you can set various defaults like a default user name for new entries (created in this database).
On this page you can specify various encryption-related settings. Only change this settings when you really know what you are doing.
KeePass has a link button on this page to compute the number of key transformations your computer can do in 1 second. If you for example only want to wait 0.5 seconds, half the number resulted from the benchmark.
KeePass databases can be compressed before being encrypted. Compression reduces the size of the database, but also slows down the database saving/loading process a bit.
It is recommended to use the GZip compression option. This algorithm is very fast (you won't notice any difference to saving the database without compression) and its compression rate is acceptable.
It is not recommended to save databases without compression.
On modern PCs, saving files with compression can actually be faster than saving without compression, because the compression process is performed by the CPU (which is very fast) and fewer data has to be transferred from/to the storage device. Especially when the device is slow (like saving to USB stick), compression can reduce the saving/loading time significantly.
Templates are a great way to predefine often used user names or additional fields, or combinations of each.
First create a normal group in the main window and then set it as the templates group in 'File' -> 'Database Settings' -> tab 'Templates'.
In order to create a new entry based on a template in the templates group, click the drop-down arrow of the 'Add Entry' toolbar button and choose the template to be used.