gps for adventure travel, what to buy?

[maskdesigner]

I have ~no experience with gps systems, but my dad wants to buy one
for when he goes on an adventure travel trip with my sister.

He's looking at lower cost models and I want to know if there is a
good hand held gps for that purpose.

Just briefly looking, the Garmin Oregon 550 seems very nice but he
balked at the price.

A few features I think he must have are:

1. updateable maps, preferably with a common expansion card format.

2. good battery life.

3. a legible screen, his eyesight isn't the greatest (small fonts
would be bad if he does not have his glasses).

4. waterproof.

5. fast to pick up satelites and quick to operate.

6. straightforward user interface.

7. USB interface.

8. world wide maps available.

Nice features would be:

1. the ability to also work as automobile navigation.

2. color screen.

3. mp3 player.

I could be way off in what I should be looking for. Like I've said, I
have no experience. Please let me know what I should be looking for.

Thanks for the help.