Well, everyone has their own preference of how to render their animations. I do prefer the rendering of each frame into their own individual frames, just because rendering does take long and if the computer crashes, you don't have to start all over... Think if you have like a 10 minute animation and you're on the final scenes trying to save it to a movie file, then all of a sudden BAM, your computer goes out, you are forced to restart. What a horrid nightmare
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To put them back together, you need any kind of video editing program. In most cases I'm sure any would do (I never really dealt with this situation before.. well, for a REALLY long time). You just stick them together, make the video go 29.97 fps, and there you go
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