The best soil for vegetables is a rich, organic soil. If I were you, I'd mix fresh topsoil and rotted manure and/or compost into the top 8 to 10 inches of your soil. The sand is not bad so I'd just till all the amendments into what you already have. Just remember, that for success the vegetables need a spot that gets at least 6 to 8 hours of direct sunlight a day. I'd also mulch the beds once the plants are up and growing to maintain a consistent soil moisture. For flowers, you can grow any annual or tender bulb that you find attractive and you have space for. Check out our Plant Encyclopedia on this site and visit the annual flowers section. Tender bulbs such as gladiolus and cannas are also nice."