Help with FFT mode

Matlab may have free trial version. There is also has a free version called Octave. Or you may find other fft tools around.

Alternatively you can inject one sample in the frame(otherwise set to zeros) and you should get a cosine/sine wave output at a given frequency(depending on sample location within frame). You can also reverse that by inputting a sine wave then you get a nozero sample surrounded by zeros.

Scaling is well documented with example coding in the fft use guide. I don't really remember or know the details of the current core. I used to just shift divide my output by number of bits = exponent (as far as I remember). Note this is not a standard approach but done to the convenience of altera engineers, they have used internally a representation somewhere between 2's complement and standard floating point.

Scaling of fft in general is not standardised across various tools so keep that in mind.