Ok I feel helpful today so...
1. Swaping WILL NOT DAMAGE the laser unit or any part of the saturn. The simple reason is that unlike the highly destructive psx swap the saturn is a smart console. If the unit senses that the motor has stopped moving (either because you are holding the disc or something has jammed it) it immediately cuts all power to the motor. It then waits a bit and tries to restart the motor, again stopping if it senses that it isn't moving. The psx on the other hand will continuosly attempt to power the motor and spin it, this is why psx drives burn out so much when you try to swap on them, it's too stupid to realize the motor can't move and tries to force it anyway. While in practice swaping on a saturn DOES cause some damage it is so minimal that you would have to do it several thousand times (in the 100,000 range) to actually have any noticable effects.
2. Swaping without any carts is simple. First insert the cdr into the drive, power on, when you hear the laser unit move (a gear grinding kinda woosh sound) swap it with the original, the drive reads the security at a slower speed, when you hear the laser unit move again swap in the cdr again and off you go. If you see the cdr spinning faster then slower than faster, etc, you were late on the second swap. The first swap is not very time critical but the second one is. If you missed it you can repeat the swaping again without having to reboot (since the saturn is looking for the security ring again). To practice take the case of the saturn and swap with it off, watch the laser unit move and listen for the sounds to get used to it. Once you get good at it just put the case back on.
3. Swaping with a cart is even easier. Just insert the cdr, then in the menus select to start the game, AS SOON AS YOU PRESS THE BUTTON swap in the original game, then swap back to the cdr like above. Simple.