Bud, all you need is a bathroom scale to get a good ballpark figure! Just weigh yourself first then get on the scale again holding the airplane. If you have differential already mixed in then try that first, if the turns are good you shouldn't need to mix rudder. In regards to the flaps, they are very effective and allow you to come in steep for short field landings. I only use them on light to no-wind days though, otherwise you don't really need them. Now when you fly yours on floats, that's a different story, they're really going to come in handy especially since you'll be heavier, and they'll give you that extra lift you'll need at the slower speeds for water landings. You will however have to dial in a bit of down elevator when you deploy the flaps, miy setup is 8% at full flaps and that seems to work really well for me.