How to set up Beanstalkd with PHP

1. If the worker isn't taking too long to fetch the feed, it will be fine. You can run multiple workers if required to process more than one at a time. I've got a system (currently using Amazon SQS, but I've done similar with BeanstalkD before), with up to 200 (or more) workers pulling from the queue.
2. A single worker script (the same script running multiple times) should be fine - the script can watch multiple tubes at the same time, and the first one available will be reserved. You can also use the job-stat command to see where a particular $job came from (which tube), or put some meta-information into the message if you need to tell each type from another.
3. A good example of running a worker is described here. I've also added supervisord (also, a useful post to get started) to easily start and keep running a number of workers per machine (I run shell scripts, as in the first link). I would limit the number of times it loops, and also put a number into the reserve() to have it wait for a few seconds, or more, for the next job the become available without spinning out of control in a tight loop that does not pause at all - even if there was nothing to do.

Addendum:

1. The shell script would be run as many times as you need. (the link show how to have it re-run as required with exec $@). Whenever the php script exits, it re-runs the PHP.
2. Apparently there's a Djanjo app to show some stats, but it's trivial enough to connect to the daemon, get a list of tubes, and then get the stats for each tube - or just counts.