MySQL database replication for Huge database (no replies)

Hi There,

I am going to set up Master/Slave replication between two MySQL Servers for Database of 50GB.

Actually restoration of that database take around 10 hours.
I am not sure how I would implement all these steps successfully while we cant stop our production database for this long time.

1. Taking backup of production database with read locks and with unlock table switch?
I am not sure what the statement "FLUSH TABLES WITH READ LOCK" will do?

2. The most important thing is that restoration of production database at SLAVE will take around 10 hours and during this time so many new data would have been entered in production. Is this possible that Slave server replicate all that new data which obviously not included in the backup?

Can some one please guide but I cant keep production DB down for long time and keep it READ LOCK as well.

Thanks

Mahmood