When you say "at our timeshare" I'm not sure if you mean a Disney Vacation Club timeshare or an off-site property. If you're staying off site, then unfortunately, you are no longer able to pre-order the PhotoPass CD. If you are staying at a DVC resort, then you are eligible to pre-order a discount CD. The procedure for this is slightly complicated. I STRONGLY suggest you go to the wonderful independent website stitchkingdom.com. At the top of the home page, there is a tab that says "definitive guides," scroll down there to find the "to Disney's PhotoPass" page. Near the bottom of that page is the complete scoop on how to get PhotoPass discounts.
As for your second question -- I'm not sure how old or what gender your twins are, so I can't give you totally specific information, but my general tip for travel with twins is: Don't assume that they'll want to do the same thing all the time.
My twins' park activity preferences could not be any different. I have one that loves thrills; she was begging for more Space Mountain at about age six. While the other began riding this only reluctantly at age nine. Similarly, one will wait in line for any character interaction, while the other is fine with Mickey, but has no interest in waiting around for a hug. My suggestion is to make sure you ask your twins what it is that they want to do individually as well as together. This might mean splitting up for a while. To facilitate this, we ended up bringing two single umbrella-style strollers and clipping them together when needed. This allowed up to transport the twins while together and apart. You can read more about this
HERE.