Overwriting template text & Multi-line function

Hello Adobe people.  I designed a whole lot of forms for a client who initially wanted it in Word, but now wants to send it to their staff as an editable pdf.  So far everything I've done is fine except for two issues:-

1) The forms are set up as a questionnaire.  How do I make the questions be automatically overwritten with the answers without having to manually go and delete the question text first before typing the answer.  Also can I change the colour of the answer text?

2) Set a field with multiple lines.  If the answer is long, I want to keep the font size the same and not set to auto so that it becomes really small.  I've set to multi-line with a font size of 8.  When I type to the end of the box, it just stops and won't let me type any further - no scroll button running down the side appears.  I'm assuming that is what the multi-line function is for?  How do I get more text into a field box with the multi-line function without having to reduce text size to auto?

Please help.  Deadline looming,