Hi,
I can absolutely help you with the fill-able form.
However, i did some research and i can't seem to find a case where a filled form can be submitted directly to OneDrive. There have been recent upgrades from adobe that let users sync their pdfs with their onedrive account, but thats it. My research may be inconclusive, but seems like this is not supported.
About filling forms on mobile; Its do-able. The catch is to use Adobe Reader using IPhone/ipad instead of the default pdf viewer. Same goes for Android.
Let me know your thoughts and looking forward to working with you
cheers,
Basil