I can't emphasise enough how important good paint is for an irreplaceable project! Get Rustoleum's 2x coverage for a little bit more, but it's well worth it. The difference in speed and quality is AMAZING and well worth the investment.
Ignore this section if you're going to sand or scuff it anyway, but I've found that using Zinsser primer makes life so much easier, and it adheres to EVERYTHING. Metal, too. It's literally the best; don't bother with anything else if you're spray painting furniture. Read a guide at this site.
In terms of quantity, always buy at least one more than you think you'll need, because if you do it correctly (especially with spindles), there will be a lot of overspray to avoid drips, lines, or runs. It's worth it to do things correctly the first time!! Because primer soaks up so much paint, you'll need at least one extra can of your colour if you want to match it as closely as possible to the lid colour.
Layers are the key to a great spray painting job; be patient and work one layer at a time. Also, too hot and it will be chalky when it dries, too cold and it will be forever.