Hi, i'm newbie in DSLR camera and plan to buy Nikon D3100. I need some advice before i buy it. My main use on this camera is landscape and portrait picture, hence I plan to buy 2 more lens which are

1. Nikon 55-200mm f/4-5.6G ED IF AF-S DX VR Nikkor Zoom Lens
2. Nikon 35mm f/1.8G AF-S DX Lens

Do you think these lens are reasonable choices? Is external flash a necessary to have?