I hope you enjoy the XD40 service, I love mine. I'm one of those mysterious left hand / right eye dominant people you speak of... so I'll try to give you a few tips from my own experience. :wink:
First, general southpaw handling of the pistol. I never use the slide release button, I always slingshot the slide closed. What I mean is that I grip back portion of the slide with my right hand, pull it all the way back, and let go. I've heard that method recommended anyway, as it does not require fine motor skills that might not be functioning properly under a high stress situation. The ambidextrous mag release is nice... you can use either your thumb or index finger, whatever you find is faster / easier. The hardest part for me is locking the slide back. After a bit of practice, I am now able to do it quite efficiently... keeping a solid grip on the pistol with my left hand, I use my right hand to pull the slide back (as if going to slingshot), then "sweep" my left index finger up the frame of the gun. The corner of the slide release catches the flesh in my finger between my first and second knuckle, and it gives enough force to push the button up to where it will lock the slide.
As for the right eye dominant... when I first started shooting, I would just close my right eye and use my left eye. If you can avoid doing this, please do. After doing some reading here and talking to a couple friends, I found that by simply changing my stance / head angle, I can align the sights with my right eye very easily. Now I shoot with both eyes open, letting my dominant right eye do the focusing on the front sight. I found this more comfortable to shoot... I wish I had started doing this earlier.
In any case, the best advice I can give is just to experiment a little bit, and do lots of dry-fire practice at your home. Once you find a technique that feels like it will work for you, practicing it will help write it to muscle memory, and then you'll be able to do it easily. Good luck and enjoy the XD!