The standard application of tedana involves (1) estimating S0/T2star, (2) calculating the OC time series, (3) applying ME-ICA to generate ICA components that can be used to denoise the data, and (4) denoising the OC data with those ICA components. Tedana will output both the OC data without denoising (desc-optcom_bold.nii.gz) and the denoised OC data (desc-denoised_bold.nii.gz). You can also use the ICA components generated by tedana to denoise your OC data in a different space (e.g., the MNI-space OC data produced by fMRIPrep), which is what I typically do, or you can use the denoised data and register it to another space.
Basically, the answer to your first question is “yes”, and the answer to your second question is “you can denoise the OC data or let tedana do it, and OC and denoising are not mutually exclusive.”