Platform can be the way to go in your case, but a lot of adaptation should be done for the controls. First of all, deactivate the default key mapping. You will then need to make a big event where you check on current inputs, current animation of the sprite, and change the animation according to inputs. Then, you can use the "simulate controls" action of the platform behavior to control the movement of your sprite.
It can be a lot of work for lots of animations though... I would personally do multiple events like "If left key input -> if currentAnimation = left, simulate left, else play left animation", ...
It all depends on how you want to map your controls then.
Don't use other people thread for your own problems, create yours. That said, you need to give more infos. Construct 2 will send your datas without problem using the "AJAX" plugin, and the problem is most likely in how you use this plugin, or in your server.