When planes "balloon", they are setting the AOA of the wing too high. This can be caused from anything from over speed to not enough down thrust to CG and incidence issues. You must first attempt to determine the root cause of the problem, and it may be more than just one item. Download the trim chart I posted or another similar chart. I'd first check for thrust issues, trim for level flight at 3/4 throttle, then chop the throttle. Does the plane descend in a nice arc or does it sharply head down. If it is the latter, you don't have enough down thrust, etc. The try dives at idle to check for incidence, etc. as indicated on the trim chart. As BritBrat mentioned, everything is interdependent, i.e. a change in one thing effects everything else, so you end up chasing configurations around. To really trim a plane out well, it often many small adjustments and many flights, but it is worth it in the end.

The part about the trim changing during the day is curious. It may be possible you are having expansion/contraction issues with the control rods, or maybe a fuel tank issue is shifting your CG a lot. If you are using the plastic pushrod (Nyrod, etc.), they suck. They will change a lot with temp and cause you to retrim all the time. Replace them with pull-pull cables or steel rods, etc. and the majority of the retrim issue will probably go away.

Here where I fly in Nebraska, we consider wind anything over 30MPH. Anything less is a gentle breeze. So I have some experience with wind. What effects model performance in wind more than anything is wing loading. A lightly loaded model has a lot of wing for it's mass, and hence is pushed around easier in the wind. The low mass (read low inertia) for the area of the plane is easily upset by wind gusts. For that reason, sometimes it isn't always best to build as light as possible in areas that have more wind. The extra mass (assuming you don't go overboard) actually helps penetration in gust conditions. 4*'s are lightly loaded planes. I'm 95% sure what your perceive as a wind handling issue is due to the light wing loading on that plane.

Cheers