I have a lot of symbols to swap. Is there an alternative to using the Swap Symbol feature individually on each instance in the Timeline?
Well, you can't select several instances and swap them all at once. However, if you are planning to replace an entire tween this way, you can take advantage of an interesting Library feature. Say the instances you want to replace are all based on a symbol called box. To quickly swap them all with another symbol called circle, first either create the circle in a new file or copy it into a new file. In the new file rename the circle symbol (the symbol, not the instance) to box. Now the new file has something called box that actually contains a circle shape. Then copy or drag box from the new file back to your original movie's Library. A Library Conflict dialog box appears, asking you whether to rename the new box or to replace the existing box. Choose to replace, and you see every instance change. Play around with this trick to fully understand it because it will replace every instance used in the entire movie.
Every time I open a.flafile that my co-worker created, I see a Missing Font Warning dialog box. What does this mean and what should I do?
It means your co-worker created a text block (of any type Static, Dynamic, or Input) that includes a font that you don't have installed on your machine. If you're careful never to touch any of those text blocks and if you send the file back to your co-worker when it's time to publish (or you install the font on your machine), then there's really no problem. However, if you need to edit those text blocks and you're not going to buy the font, this dialog box provides a way for you to specify (in one swoop) which font Flash should substitute for each instance. Just realize that this is an authortime issue and is unrelated to the character options for dynamic and input text.