Also, you don't cause errors when you compress and decompress using a lossless compression format (as the name sort of implies).
That's not how it works. You can totally hear clipping or noise even as an amateur. Just as an amateur photographer first thing first learns to look out for overlit skies and hilights that aren't really recoverable at all unless they perhaps have access to the camera's RAW files. But unlike in photography, in sound work you typically need to process as well as sum multiple recordings, all while not blowing out the peaks that might just happen to line up.
If anything, dealing with the large dynamic range of 24-bit is easier for the amateur. An experienced pro would probably have a good bunch of tricks in his bag should he really have to mix music in 16 bits, enough to produce something that doesn't sound horrible. The amateur would be more likely to struggle.
In practice, fixed-point or floating-point is better depends on the operation you plan to use and whether you have a good idea whether you'll be able to stay in a fixed range ahead of time [1].
[1] The loss of 'footroom bits' corresponds to the extra resolution lost whenever the FP mantissa increases - http://www.tvtechnology.com/audio/0014/fixedpoint-vs-floatin...
It's the same rationale for doing calculations in full 80-bit or 64-bit FP even if you don't need the full bits of precision -- if you start your calculations at your target precision, your result will have insufficient precision due to truncation, roundoff, overflow, underflow, clipping, etc. in intermediate calculations.
In theory, if you knew what your editing pipeline is, one could mathematically derive the starting headroom required to end up with acceptable error, but in practice that's probably a very risky proposition because 1) you don't know every intermediate calculation going on in every piece of software and 2) errors grow in highly non-linear ways, so even a small change in your pipeline might cause a large change in required headroom [1].
[1] https://en.wikipedia.org/wiki/Numerical_analysis#Generation_...