Client - Freelancer selection/hiring timeframe

[#1]

Is there a set amount of time the client has to make a decision to hire after posting a job/project and receiving proposals?  It seems that one could get themselves into a bit of trouble bidding on too many jobs if there isn't a set amount of time, restricting the client to make a decision on submitted bids/proposals.

[#2]

No, there is no time frame set as to a client hiring a freelancer. Some hire in just 15 minutes of posting the job. Some take a few days. After 30 days of inactivity of a client, the job will automatically expire. But there have been freelancers here who have received a job invite months after a job automatically expired.

As for bidding on multiple jobs, don't expect to get all of them. If you do find yourself working on 2 or 3, and are presented an offer of yet another job, you can let the client know about when you can start on their job, or stop submitting proposals until you get a handle on being able to work on mutiple jobs. 

[#3]

 "get themselves into a bit of trouble bidding on too many jobs"

Well... as a freelancer, you can always say no. And there's nothing a client can do about that. And no negative repercussions.

If I bid on 10 jobs, and EVERYBODY wants to hire me, then I could simply say no after I accept the first 2 and get too busy for the others.

There are OTHER FREELANCERS also bidding on the same jobs. Clients I say no to will be able to hire somebody else. (It won't be me... but that's what they get for being too slow.)