NO! Never go for a 550W PSU..that is only 20 dollars. Get a skyhawk or enermax PSU...you have to be willing to pay some cash for a good power supply, If you don't need that much power I will recommend this, many people including myself have had it for a year without problems:
1. 1 post per topic is sufficient
2. The specs on that PSU look reasonable, but I doubt it would live up to them. Spending a little more would be a good idea.
3. What sort of PSU you need really depends on your specs.
If you don't need that much power I will recommend this, many people including myself have had it for a year without problems: