When rendering to a finishing quality codec like Pro Res 4444, will it cause any issues, when I turnover to sound, if the audio bit rate is 32 bit float vs 24 bit? In our Premiere project, everything else is 24 bit.
AE is the worst audio processing app on the planet, so whatever you do try avoiding any sample rate or bit depth conversions like the plague regardless whether that's on import, on the timeline or on export. If there is really different audio types involved, convert and conform them to the same specs so AE only needs to pass them through on render.
The pixel bit depth settings have nothing to do with the audio. If at all, those options are related to the specific CoDec options and AE will simply handle it quietly behind the scenes. Again, simply make sure all settings on that front are consistent in the first place so AE doesn't make a mess.