Important thing when you buy a domain name.

Do not buy a domain name thinking the name is great, IMPLEMENTATION is the key here.

Before buying a domain name and hosting, ask yourself:

1 What can I do with that domain name

2 What service (unique) can I offer ?

3 Am I likely to get repeat customers ?

4 Do I have experience in the field that I am throwing myself in?

Don't buy a domain name blindly thinking "The domain name is great, i can make a good site with it"

A domain name is only a VERY small percentage of a business, just like Chevron Texaco or Linux would be just as popular with any other name.

That is true.  Branding will always be the most important part of building a name.

it seems your list of things is more for starting a business so.. heres a few things to consider when buying a new domain name:

1...is my domain name to long for the everyday person to remember?
2...how catchy is the domain name? is it boring? if its boring people may want to NOT remember it
3...does it relate to the content of the site, and/or the business (if it is a biz)?
4...how much am i paying for this domain? if it already has PR value it may be worth any where from $10 (for low like PR1) - $100 (for higher ones like PR7).
5...is it worth it? will your income be more than your expenses? make sure you are making MORE money from your site then you are spending on it as a whole. this is the whole point behind this. do not end up paying the higher yearly rates like 15$ a year for a crappy domain you wont want 2 months into the subscription.