I'm pleased as punch to answer the very first question for this blog ...
As a long-time Snarkling [go to http://www.misssnark.com/ if you're not sure what this means], I’ve often wondered about the differences between US and Australian protocols/etiquette for contacting agents. In particular, it seems to be encouraged over there to ‘query’ (i.e. send a cover letter plus pages and synopsis) multiple agents simultaneously, while here it seems to be frowned upon to approach more than one agent at a time. And since it has recently taken me 9 weeks to receive a rejection just on an initial query from one agent, and 8 months for a full manuscript from another, I could conceivably die of old age before I finish this process! What would happen if I applied Ms Snark’s advice to the Australian market, and just ‘queried widely’?
Because there are hundreds of literary agents in the US (mostly in New York City), it certainly makes sense to query widely there. Australia has a mere handful of agents but this is also one of the reasons why it takes so long to respond to submissions - there just aren't enough agents to go around.
I always presume that authors who send queries/submissions to me are also sending them to several agents, and I don't mind this one bit because I know it will take me a while to read their submissions - like most folks in publishing, I can only read them on the weekends in between housework. I would never expect an author to submit to only me - it's nice if they want to, but it's safer to hedge bets.
Having said that ... not all agents feel this way, so it's wise to check the agency's website or, if the information isn't there, call or email them before you submit to other agents. If you aren't able to find out what their policy is, presume that they don't mind if you submit to other agents and, as a courtesy, tell them in your cover letter that you've sent it to others (you don't have to say who).
If the agent you really want to send it to first says not to send it to anyone else at the same time, it's your prerogative to not send it to them at all if you don't like that policy.