[Standard warning: that site is adamantly pro-only. There's a lot of good information there, and if you register it makes searching easier (no image verification thingy), and lets you download attachments. And anybody can register, but only people who build or fix houses for a living are allowed to post. JLC members can be really mean, nasty, rude and/or obnoxious bullies when enforcing that rule. You have been warned...]
That thread is about doing it from the inside, but same basic idea. You definitely need to find a way to drain the cavity, somehow (occurred to me later: you could just scarf the front of the bottom plate). And remember to bug-net the openings...
Worth it to spray the edges, like Dave said. Air-sealing's critical.
The possible problem is that because you've insulated, the cavity's a lot cooler than it used to be (in jargon, you've changed the hygrothermic balance of the assembly). Basically, less warmth = less evaporation... So there's a risk.
It might be okay, it might cause problems. Depends on the specifics of your house, how much air leakage there is, etc.
Moisture meter. Check the wall cavity before/during/after a bit of rain.I guess my last question is how do you determine if/when moisture might be a problem? They did ask me where I lived....
Or: open a wall somewhere, just enough to take a peek. Look for drip-marks on the backside of your siding, especially around & below windows, etc.
If you mean after insulating - the first sign of moisture issues, usually, is peeling paint on the siding.