Welcome to the forum.
Well, first of all, the Q phone is a great phone and I think you be glad you got it...but you ask good questions:
1. The problem with forums is that only people with issues post for the most part, unless you are a person who enjoys sharing positive on tech devices. So I can assure you there are many times more people who do not have any issues with there phone than the ones who post issues. That said, there was one issue with the Q that some people experienced that related to powering the phone back on which was fixed with the third ROM upgrade. I owned two Q's (I had several from Motorola prior as well, since I was a developer for the Q) and I never experienced any issues with the phone locking up on power up. I have several friends who have the silver and black Q's and they have not had the problem. My wife did get a Q with the issue, and Verizon replaced it and she has not has any issues since. I do not believe you will get this issue, but Sprint will replace it if you get the issue.
2. Battery life is an issue with all PDA devices, not just the Q. I would recommend you get an extended battery if you plan on using the Q for long periods of time without being able to refresh the charge (car charger or home charger). I was able to use my Q for most of a day without issue, but that really depends on how you use the device. If you use the car charger once during the day if you are are away from home, you should be good to go. But the extended battery gives you freedom and you will not have an issue when using it.
3. I have never used any of my PDA phones without data, but you can have the carrier turn it off and you will be fine. However, a lot of the features like Web browsing and Email will not function without it unless you are connected to your PC.
4. You can download programs to your PC and install them to the device. You can also get Internet access through your PC connection to the device as well.
5. All carriers are good about replacing defective devices. So don't worry about getting a 'lemon'.
Hope this helps. A Q for $30 is a good deal.
Rob.