First of all, I apologize as I am not a "systems expert" and may not understard most of what is said.... but I hope to get some advise from the experts:
I do not have a firewall, but one will be installed. I do not what to jeopardize my web access and internet communication from different programs (yahoo, msn, google-earth, web searches, online databases, file transfer, etc).
How can I leave a "door" open BEFORE the firewall is set in place, so that after the firewall is set, I can still mantain internet access at will???
In other words, how can I protect my communications before the firewall is set?
You don't really need to do anything before implementing a firewall (correct me if I'm wrong because I may not be thinking deep enough). Simply install it and depending on the kind of firewall you get, it either performs a walk through with you so you become acquainted with its features and abilities and it can become acquainted with your computer, or it goes straight to work.
Most firewalls are smart enough to know what legitimate and safe Internet traffic (or traffic pattern) would look like, and so even after implementing a firewall, you would still be able to surf the Internet and do what you normally do.
For the first few days, you'll be interacting with it a lot because it'll be learning about your system and about what you normally do on your computer, so you may receive messages from it basically asking you if such and such program is authorized by you to run, if so and so program is authorized by you to access the Internet, etc.