Extraction or non-extraction depends on how much your teeth are forwardly placed or over-lapped, in other words, how much space required to straighten your teeth.
Yes, there is another way to straighten your teeth is re-shaping your teeth size( proximal slicing), but it is done when the space requirement is comparatively less.
Next Steps
NO, there is no negative long/short term impact on removing your teeth, just you have wear retainers as per instruction by your orthodontist