The PDF from Photoshop should be fine.
I would save as PSD first and then as PDF without the Photoshop editing compatibility just for file size purposes.
If you want to bring it into InDesign definitely save as PDF from Photoshop. PSD will rasterize everything. With PDF the vectors in the text will be preserved.
2: What if I import the Photoshop PSD file into InDesign and then exported as a PDF? I know I am grasping at straws here but trying to get away from recreating yesterday's work using InDesign, even though I think in my heart, that's the best alternative.
If there is a vectors or text in photoshop save as pdf and place in indesign.
Thanks Bob. Great news for my workload today.
Salah, yes there is text so Photoshop to PDF it is then. Thanks.
There shouldn't be a problem with saving a copy as PDF—any vector layers or type will remain as vectors unless you've flattened the PSD or rasterized the layers. You would have to watchout for the PSD's color mode. If it is RGB, black type would get converted to 4-color and it may or may not overprint, so you would want to inspect the ad in AcrobatPro. I don't see how placing the PSD in ID would help.
1: Will a Photoshop document exported as a PDF be significantly lower quality than if I created in InDesign
If the ad is in color, Photoshop will by default handle black text differently than ID, which could have a significant affect on quality. InDesign's default [Black] is CMYK 0|0|0|100 and set to overprint. Photoshop's default black will be a 4-color mix in either RGB or CMYK mode, and won't overprint. So for black text you have to make sure the color is set to 0|0|0|100 and the blend mode should be Multiply if you want an overprint.