1) Yes, your listing agent matters. look for the top listing agent in your area. These agents are savvy in the marketing your home, that is why the he/she would be the top in the area. A top agent usually knows the market and has many listings that draw people to them. If you go to an agent that has no listings and she/he says to you.. well, "I will only be working on your home" that other agent is to busy to give you their full attention...it is just a pitch to get your listing, to get business.
2) Yes, it is a lot about price and timing. A good listing agent will come to you and tell you an honest price to get the home sold. If an agent comes in tells you what seems to be a higher price, usually it is just to get your listing, letting you think they can get you more money when rather it is just to get the listing.
Make sure your agent SHOWS YOU what will happen, each and every website, each advertising piece , previous (current) mailers, previous company ads, previous personal advertising. These things matter. Most of the top listing agents will have this information available for you. The point is to sell your home. Top listing agents will already stream of buyers that are looking.
The whole "staging" and "international" marketing thing is not really in play.. clean your house.. make sure it looks good, your listing agent can help with that.. how many times have you heard that your neighbor sold his house to a guy that moved from Madrid, Spain because he saw the house on some international website.. uh, none. Again, it is about the listing agent marketing plan.