In my opinion, yes. They are all bullets. They all feel the same to me. They all numb me and have the same buzzy, cheap vibrations. The only difference I have ever seen in bullets is some are weaker cheap, buzzy vibrations and some are super strong, buzzy, numbing vibrations. This is how bullets work for me, though. Others are okay with them.

Correct, bullets are not long-lasting. Ever hardly. I have never had a bullet vibrator last longer than a couple of months. I've had more stop working after one use than anything.

Oops. Forgot to answer your question about interchangeable bullets. Yes, usually, you can remove the old, non-working bullet from the toy and insert a new one as long as it's of similar size. I've been able to do this with every toy that took a bullet that I've owned.