Do you have to reformat an SD Card before you can copy its contents to your PC? My phone has been stuck in a boot loop and I need to safely retrieve the contents via card-to-PC transfer, then PC-to-new card, then new card-to-phone, etc. I read somewhere on here that you must reformat your SD card before you can connect it to your PC to copy its contents. Is this true?

If so, will I lose my stuff from reformatting my card? Every time I've tried reformatting my card, I get a dialog box that tells me all my card's contents could be destroyed if I go ahead, so I refrain.

Seems like it would be pointless to try and retrieve my card's contents if I must destroy them first. I'm fairly new to this stuff, so please excuse my lack of knowledge for it.

Also, once I get all of my content into my new SD card, do I need to format the new card when inserted in my phone? I notice that whenever I put an SD card with files on it into a new phone, I get a prompt saying that all contents could be destroyed if I format, even though I want these files on my phone and certainly not destroyed. 

Thanks for any and all questions answered, I appreciate it.
No, you MUST NOT reformat it before copying! Formatting a storage device means to prepare it to hold files, and it will delete everything on it (see the tag wiki of the formatting tag for details). So yes, formatting woul imply losing all contents on the formatted device (in this case, from your SDCard).

New cards usually come pre-formatted, so there's no action needed either: Simply insert and enjoy. I never heard a device prompting you to format a newly inserted card, and I've had some of them. Of course, a warning is issued when you manually select to format a card, so you do not accidentally fall into such a trap.