No worries, I am actually a newbie as well, I have only been using Construct for a couple of weeks. But as I have a lot of time on teh train during my commute, I have pretty much read most of the manual and spend time doing searches on the forms each day. I have also started downloading the CAPX files that others post when they ask questions and using them to try to come up with my own solutions. So it has helped me pick it up fairly quickly.
For structuring your code the easiest way I have found is to create multiple event sheets, for example one for player movement, one for enemey behavior, one for any events tied to that particular layout, etc... this gives you a much better chance of finding issues if you know where the code that effects a particular object is.
For alternate controls, you can use the platform simulate control action. This lets you say for example, if they hit this button, simulate the platform Up action, or the platform left or right action. That way you can have other buttons that respond the same as the arrows do. You can also just use the keyboard object and fire off events based on keypresses. Another option is a plugin that lets you create alternate control schemes.
One thing to keep in mind with creating your control schemes is that it is not always the best idea to translate your keyboard or controller based actions directly to touch screen. For example, if I want my character to do a wall jump, then on a controller I may want them to hit the jump button + the opposite direction of the wall on their controll pad. Or even more complex actions that require multiple buttons being used together. On a touch screen usually thumbs are being used so you can't easily do multiple button presses like that, so for touchscreen I actually combine or simplify my control scheme. For the above example, if it was touch screen, then for my wall jumping, I just require that they hit the opposite direction on my virtual directional pad, instead of forcing them to hit other buttons at the same time.
While it may take a bit more time on my end, the experience is better for those who are not using a controller or keyboard. You should go through the tutorials on intro to construct as it has you create the ghost shooter game that using mouse shooting, also the two tutorials on creating platformer games are great as well here they are:
Beginners guide (Ghost Shooter Game): scirra.com/tutorials/37/beginners-guide-to-construct-2
Creating a basic platformer in Construct:
I am currently working on a series of tutorials on enhancing or adding more advanced platform behaviors to a game that I will be publishing to the tutorials section in the coming weeks.
Welcome to the site and as a fellow newbie here, I look forward to seeing what you make!