Cloning my win 7 partition to external HDD w/ Mac OS extended format

Hi, I recently switched from a Mac to a PC. I cloned my system partition of my PC to my external hard disk, and I only realized later that the external HDD was in a Mac OS extended (journaled) format. I thought I would have to format that partition as NTFS and re-clone afterwards. I tried to remove that partition using Disk Utilities on my Mac but got an error message. Surprisingly, though, when I connected the external HDD to my PC, I can access that partition under My Computer, and when I open Disk Management that partition is listed as NTFS.

1) How can I tell if the cloned partition on my external HDD is ok?
2) Should I reformat it and start from scratch instead?
3) If so, should I be making an image OR a clone of my system disk (so that I can boot from my external HDD and restore my system if my internal HDD fails)?

Thank you!!

I tried to run Partition Wizard to reformat and re-partition my external HDD, but the program keeps crashing as soon as I connected my external HDD to the computer.

I can see the external HDD in other programs such as EaseUS and Macrium Reflect, as well as in disk manager. Does it mean that the problem is with Partition Wizard? What should I do instead (to repartition my external HDD)?