Hi MD,
Most of your questions depend on the agency you are with and the company with which you are placed.
I'll try to answer your questions in order:
a) 40 - 60 hours + a week currently the norm
b) If you are contracted to work outside the UK, the agencies I've been with generally arrange travel, recompense you or subsidise. Accommodation is also generally paid.
c) I'd recommend using an umbrella company such as Orange Genie - let them sort out all the details. Don't bother setting up a limited company.
d) Take out a multi-trip business insurance policy. Mine costs £150/pa. Arrange a loss of earnings policy (Scottish Widows run a reasonably priced scheme)
e) Some agencies will recompense excess baggage related to tools. I've never been charged excess out of the UK with a toolbox. I always get charged if flying out of Germany!