There are a lot of very good effects houses around, and if you're not picky about how the shots get done (i.e. model vs. cgi vs. physical effect), the field becomes wide open.
I have a friend at Rhythm & Hues ( http://www.rhythm.com/
), which always does excellent work, with an emphasis on CGI and digital compositing, but they're very
high end, and so it's hard to get on their schedule unless you can pay rate-card prices.
About a decade ago I was prepping a feature which needed all the effects you list, and was planning to use Alterian ( http://www.alterianinc.com/
), and was pleased with the work they do (mostly physical, which is how I wanted the effects done), and being less well-known they're more likely to cut you a deal.
But for basic stuff like that, also don't discount the "little guy." One of the principals of HogoFilm ( http://www.hogofilm.com/
) is in the office next door to me, and I'm always impressed at the quality effects he brings in for effectively no money.
Bottom line, though, sit down with your storyboards, decide what you need, and then talk to lots of people. Your final decision about who to use should be based on who you're communicating well with and who understands your vision.