Wingtube: I didn't measure mine because its too cold out.... but 3/4" = 19.05mm so a 3/4" tube would probably work just fine in a 19mm setup(the metric is just 0.002" thinner- literally a hair!).
Landing gear option (easy, ~$50) Maynardrupp got TNT to do a special for this plane in "real" aluminum a year ago.... says it works great.
Posts 1230-1233 here:
http://www.rcuniverse.com/forum/m_47...50/key_/tm.htm
I think both kit to kit and pilot to pilot variations make for a variety of experiences. My Phoenix stock gear only bends ~one in 20 flights, and in those cases I am usually glad it did, so I just bend it back cheerfully. I also happen to use 10-15mm of spoilerons on days where wind exceeds 10 knots, so the landing speeds up and therefore it doesn't tend to drop a wing as it slows down in a crosswind. My Phoenix is <<7 lbs though, so especially on windy days, it needs some help getting out of the sky, where it is very happy!
Wing area: somewhat of a personal choice here, but manymost of the people I talk to would include the fuselage between wing roots in any wing area calculations. The reason is that the entire fuselage actually provides some lift, so by including that widest part of the fuse in wing loading calculations you are at least nodding at (probably underestimating) the very real "lifting body" fuselage contribution. I measured 5.5" fuse width, so that would add ~90 sq in to the 700 sq in actual wing area for 790. The goal of calculating wing loading is usually to estimate where in the "rock to feather" spectrum a given build ends up. Helps a lot to compare it to some old plane you've flown before when you are doing a maiden flight and landing. For this purpose I would always include the area between the wings as lifting area... so that a profile fun fly and a GeeBee can be compared on the same page.... with fairly accurate prediction of flight characteristics.
PS if you use this calculator:
http://www.anything-rc.com/wing-load-calculator.html
you get 768 sq in. That's because this calculator calculates average chord and applies it to the 28 +5.5+28 = 61.5" wingspan. Using this, my 6#11oz plane is right at 20oz/sqft.
I would generally use the 16.375 root chord across the 5.5" wide fuselage, which adds 22 sq in. and drops the loading calculated a tad to 19.5 oz/sq ft., a 2.5% (minor) difference.