A:AnswerProbably one of the Yonguno flashes. Their quality is great for the cost. Or another sb700 for $330. Look for refurbished or used sb700s. But the yongunos are cheap
A:AnswerFor indoor object shooting flash is a must. Actually more than one flashes are needed to get the desired lighting effect. There is a booklet to introduce how to use it (them).
A:AnswerYes. It supports the following functionality with the D3000:
i-TTL, M, GN, Advanced Wireless Lighting (Master, Remote, or SU-4 mode), Color filter information transferred to camera, Rear curtain sync, Slow sync, Red-eye Reduction, AF-Assist illumination, Firmware update capable