Dropping the left wing is due to torque and perhaps some Pfactor due to the usually higher angle of attack upon takeoff when flying still quite slowly. The guys are right and some right thrust would go a long ways towards reducing this. It's more noticable because you're using a larger engine than the plane was designed for. The smaller engine would do the same thing but not as strongly.

IF you were powering it in a scale manner where the power to weight ratios were the same for your model you'd be flying it with a .60 or .90. With that engine the model would have a far more accurate scale performance and these issues you're finding would be all but unnoticable. But since we modelers just LOVE to power our models with at least the power to weight ratio of such things as the P51 Mustangs it should be no surprise when our models act to some extent like the old WW2 fighters did with torque reaction and P factor from using larger than designed for props on the larger engines.

So try adding a bit of right thrust and that'll help. It may not make all of the issues go away but it's a start. As for the stall on landing you just need to fly it more attentively to avoid stalling the model. As you say and from your description it's heavier than ideal and along with the torque from the bigger engine you're getting exactly what this setup can be expected to do.