it's a little confusing at first. You don't need to worry about the output voltage of 14-16v except when you are choosing which driver and batteries you use. When you are working out how to drive led's it's the current that you need to control. Current = brightness. You are choosing a drive current of 1 amp. So you set the driver to always supply 1 amp by adjusting the trimpot (this adjusts the output current).
The driver will then always supply 1 amp. So, in your example you'd wire the Ostar up to the driver and it will supply 1 amp which means that it will be giving a supply voltage of whatever the led need in order to draw one amp - say 15 volts (which reduces as the led warms up). If you then wired another Ostar in series with the one you've already got, the driver will still try to supply 1 amp to both, which would mean it will automatically up the output voltage to c. 30 volts.
If you then hooked it up instead to 5 led's that needed 18 volts to draw 1 amp, it would give them 18 volts. It will give the led's exactly the voltage they need in order to draw 1 amp. This is very important because as led's heat up, the voltage they "drop" reduces for the same current. eg I have a Cree MC-E. If I drive it at 1 amp it will "drop" around 14 volts at first, but as it gets hotter it only needs around 13.2 volts to draw 1 amp. So, if I feed it a constant 14 volts, it will start off drawing 1 amp but as it gets warmer it will be receiving more voltage than it needs so it will draw more current, probably enough to burn it out because it will continue to get hotter and hotter.
You need to consider your battery voltage also because a boost driver needs an input supply voltage that is less than the voltage it is churning out. In your example the Ostar needs 14 - 16v so you must keep your battery voltage below 14v. You'll need to attach your Shark to a heatsink to get rid of the heat that it will produce. The lower your battery voltage drops, the harder the Shark will have to work to supply the 14-16v, so the more current it will draw from the battery, and the hotter it will get.
It sounds very complicated - probably because of my crap explanation. I'll PM you my email address and we can go through it all offline if you like. All the info is on here in various places if you do a search anyway.