Just starting

Hi, I am brand new to this whole process, but have decided that within the next year, I'd like to start on the road to adoption. I'm a single woman in my mid 30's and considering the Special Needs Program in China. I guess my main question is about how the program works. When looking at various photolisting sites, they list an agency. Are the children available only to people using that agency? So - down the line, if there's a child I'm interested in, is it a problem that I've been working with another agency? I'd also assume that children with the least significant health problems get picked pretty quick - so does it run less as a list and more as a race? My next question seems to be a popular one - but I'd love some agency recommendations, or ones to run from. Also interested in people's experiences working with an out of state agency. Thanks for any info! CK