Thought the first–does a place like Bed, Bath and Beyond or Linens ‘N’ Things count as a Specialty Kitchen Store? 'Cause I’d almost bet one could by such molds at a place like one of those, and wouldn’t be surprised if one could find acceptable molds at a place like Target–although I haven’t looked, and don’t know how price or quality compare, even assuming they are there. Silicone baking supplies have become incredibly ubiquitous over the last few years. So you could also order them over the internet, although that might take longer than you want to wake.
Thought the second. I bet a muffin tin would work. You might want to divide the batter into more than 6 muffin cups. I’m not sure how big the individual molds are supposed to be. Baking time might also be a little off. And you may have some issues with the cakes not being as pretty/easy to get out of the muffin tin as if you’d used the individual silicone molds–one of the reasons silicone has become so popular lately is because food doesn’t generally stick to it, and it’s flexible, so the mold will deform rather than the cake–as opposed to a muffin tin where the cake will give/break before the tin does.
Thought the third. I’ve never actually used silicone molds, or fixed this recipe or adapted a recipe intended for silicone molds for another use, so I may not be the best qualified person to answer your question. Hopefully someone else will come along and steer us straight, if I’ve steered you wrong.