New Guinea Impatiens is capable of withstanding full sun, but still require lots and lots of water. Feeding every 2 weeks with a diluted fertilizer is an excellent idea. Just don't use it full strength or you get lots of foliage and little flowers.

Impatiens require regular water and do not respond well to dry soil. Avoid keeping the soil consistently moist/soaked/saturated, however, or you get tall flush foliage and very few flowers. Keep the soil damp and slightly dry between watering (no drying out of soil, however, especially in sun).

If you stick your finger into the basket and the soil is dry on top but damp an 1" down, it is a good time to water. If it is damp on top, you can wait. Baskets dry out relatively fast and should be checked daily.

If flowering stops or is reduced, you can pinched back any long stems (pinch them back hard) and fertilize lightly with a diluted flower fertilizer. The impatiens should flower again in 2-3 weeks. Impatiens respond very nicely to being pinched back. If you unhappy with the looks, pinching it back will result in compact, branched plants with lots of flowers.

Thank-you for all your advice!

Happy Gardening!