Can the Snorlax on route 7 be female

The gender ratio for the 6th generation starters is currently unknown, but all starters so far had a ratio of 12.5% female / 87.5% male, or 1 : 7.

The gender of your Pokémon does not depend on your character's gender. Both male and female protagonists can have either male or female starters.

This specific gender ratio is used to make it more difficult in breeding more of them since players usually get them as gifts or Fossils rather than catch them in the wild. All starter and Fossil Pokémon are in this group.

The only way to ensure you'll get a female starter is indeed by saving the game beforehand and reloading it as necessary.

The Discount Coupon was available via Global Link until March 3, 2014 (thanks to @Jerry for finding that one out). If you got it until then, it will remain on your game until you use it or delete the save file.

For reference, here is a description of how it was done, which might apply to similar future events:
To get it, you simply need to create an account on 3ds.pokemon-gl.com, log in, register your game (use the in-game Game Sync feature to create a Game Sync ID) and click the right picture in the PokeMileage Club. The next time you use Game Sync, you will receive a Discount Coupon from the red Lady right of the PC in any Pokemon Center. You also get a confirmation on the PGL site once you've unlocked it.