A friend asked for some helpful hints to minimize expense for a one-way car rental he would like to do in July. He starting out in Geneva and wants to end up in Strasbourg. He's found the opportunity to rent at the "French portal" at the Geneva airport. He'll need the car for about 10 days.

Questions:

1. Is there a one-way charge, compared with a roundtrip?
2. How about taking the car into Switzerland, or Germany...would that be allowed, prohibited, or available for fee or no fee?
3. What is the best strategy for renting for 10 days vs. other periods, i.e. is 10 days a bad period compared with, say, a week.
4. For driving in Switzerland, would a highway fee be payable?
5. Any hints on companies to use that tend to be more economical?

Thanks for any input.