Photoshop :: Print Image Format

I want to prepare my images in PS CS6 for print. I have read several articles that TIFF files print best since they do not lose any information but sometimes you can barely see the difference from a TIFF to a JPEG. However, I have also been told by a professional wedding photographer that you should always give your clients JPEGS since it is such a universal file format. I noticed on websites like CVS photo or Shutterfly they do not even accept TIFF files.
 
what file settings are best when printing JPEGS?I would normally save a file as the following:
 
- JPEG (quality 12/baseline optimized)
- 16-bit
- 300 dpi
- 3000x the longest side
- RGB color space
 
However, when I use the 'Image Processor' in PS to save all of my open files as JPEGs, it always saves them as 8-bit, sRGB color space. I have have a few concerns with this..
 
- Do JPEGs have to be 8-bit? If so, is this ok for printing? I have heard 16-bit is best.
- Shouldn't print files be RGB color space? NOT sRGB?
- Does the dpi matter?
 
Is there any easy way to change the auto settings when saving as a JPEG in the 'Image Processor'? Or maybe I could create an action for saving? Although, I have tried this and it never seems to work properly.