do some "searching" and found an excellent post by Peter CDE, a great Moderator on the GP forum, who answers several of your questions in his post of Jan 23, 2003. Have a look. Girard Perregaux is a great watch manufacture with a long history of watch making. They also have a fascinating museum and incredible archive. People ultimately need to "buy what they like" when you get to this level of watches and be careful of "advice" from people that have commissions attached to what you are buying. Happy hunting.
Best,
Tim