Address management

[wachtwoord]

I have a question regarding address management of the default client.

Apparently it has a stock of 100 addresses (as a default) and every time you 'use' and address it removes an address from this pool and adds a fresh one.

I would like to know if:

1) this is restricted to sending addresses (e.g. only sending addresses are removed)
2) What does it mean to 'use' and address? (e.g. sending bitcoin from that address?)
3) What would cause the removal of an address on which i received BTC?

I would like to know all this since I want to determine if it is possible for me to lose BTC in the following sequence:

1) Receive BTC on some address in the client
2) create >100 new addresses 

will I still have the private key of the original address?

[cypherdoc]

you may have thousands of addresses in your wallet at one time and you will always retain the private keys to them despite whats going on in the unused pool.

[wachtwoord]

Ok great to know I have no way to mess up and don't have to send all the coins in my wallet to a freshly created address every 100 addressees (like when I updated the client to enable encryption)

Thanks