I took a look at the file, thanks for sending it over.
So, first of all, the font is being preserved correctly as far as I can tell: In the InDesign file you’re using Arial font, and FormMagic is carrying that over to the form in Acrobat.
The color isn’t working. There are 2 issue here, as far as I can tell. First, you’re using a gradient swatch in InDesign to create the grey. As far as I know, Acrobat does not support gradient swatches for the colour of text in form fields. Instead, create a regular RGB swatch in InDesign, with 100% tint, (interactive PDFs only support RGB, FormMagic or not) for the grey colour you would like to apply to the text. That should carry over fine with FormMagic.
The other issue about the color is based on your screenshot: Acrobat Reader normally highlights form fields in a PDF with a blue background. This setting needs to be switched off by the user in Acrobat Reader. That’s why (in your screenshot) the grey looks black and the background a weird blue.
Finally, regarding the line spacing, unfortunately FormMagic cannot preserve line spacing. As a workaround, instead of creating a single large text frame for all 4 form fields, separate each one into its own text frame in InDesign. This will give you full control of the line spacing.
Hope that helps!