Question about Figures

That is an accidental. Plus is essentially # (sharp) and minus is b (flat).

We don't use # and b because they do not mean the same. Plus/minus is merely a suggestion. Whether it can actually be executed depends on the harmonic context. 

These are the playing ranges. Upper, middle or lower playing range.

The > (greater symbol) I've also seen. Not sure what it is. I thought it was either an accent of sorts or a symbol for look-ahead.

Look ahead is correct.

There are also tags for voice leading, octaves, open voicing, etc.

Select a segment and try all settings on the parameter inspector. If there was a list somewhere that explained them all, users tend to skim it and quickly forget. If you change a setting and see a tag appear as an immediate result, it sticks.