Will this soup freeze well? If so, any tips and defrosting guidelines would be welcome. Also, if I make-ahead and keep in the fridge how long do...

Yeah! Awesome tips, AJ! When we all eat together in about a week or so, I'll gladly comment back the tasty results!

I freeze this all the time. I typically don't let the carrots get too soft though, because freezing makes them a bit mushy. If I know in advance that I want to freeze a portion of this recipe, I take that out a bit in advance. Then I add the spinach (or chard, if I'm using that instead, without cooking it over heat. The greens will cook up nicely when you reheat it. To thaw, I generally put it in the fridge overnight. My fridge and freezer are both very cold, so even overnight is sometimes not long enough, in which case, I thaw gently the rest of the way in the microwave. Then I typically reheat on the stove over medium heat, stirring occasionally, just until heated through. The greens should cook in that time. Also, for the record, I have been known to grab a frozen batch of this out of my freezer in emergencies, e.g., when meetings or client work cause me to run very late in the evening, or plans are changed at the last minute. When that happens, I defrost it in the microwave on medium power, stirring gently after about 5 or 6 minutes (putting it into a much larger container, such as an 8 cup Pyrex measure), and then stirring again every few minutes until it's defrosted. About storing in the fridge: this, like any dish made with pulses (lentils, etc.) should be eaten within 2 or 3 days at the very most. Lentils break down quickly, so if you want to keep it longer than 3, freeze it immediately instead. (It won't freeze as well if it's been in the fridge for a few days.) ;o)

I have frozen sausage lentil soups with great success. Thawing it in the fridge overnight prevents the lentils from getting mushier, as they might if you thaw it over heat.