I have created an interactive form using Adobe Acrobat Pro on a Windows 7 machine. Afterwards I tried using it on an iPad and the Click to Reset form does weird things, and the pages do not display properly "too small".

It depends a lot on which PDF viewer you are using.

There are many PDF viewers out there which can display more or less properly a plain PDF (but if there are some overprinting or transparency pieces on the page, they may already fail). The PDF viewing components of the web browsers fall into this category.

There are some who can actually display form fields, and allow entering data. Most of them do well, but there are some (actually, one in particular, namely Preview.app on OSX) which horrendously mess up the document when writing back.

And then, there are few which do understand some actions and (Acrobat) JavaScript. The leader is Adobe Acrobat (because it is the PDF viewer with the longest history). However, as good as Acrobat is on Windows and Mac, it anything but that on iOS and Android. In fact, it is about the dumbest PDF viewer understanding a little bit of JavaScript.

It is kind of common understanding that the leader for iOS is PDFExpert by Readdle, and for Android qPDF Notes Pro by Quoppa Software. Adobe completely missed the "mobile devices" train for PDF viewers.

The conclusion is that you have to be aware of which PDF viewer your users are using, and you will have to create your forms for the dumbest one. You may actually end up in delivering your form dumbed down, and have a mechanism which activates the intelligent parts of your form when it opens, and the PDF viewer understands the command to do that.