Diapers vs. Pull ups

So my son, Kevin Jr. is 15 months old and he has taken off his diaper a few times (luckily not messy ones just wet) so I thought maybe trying pull ups but he's not ready to potty train yet. My questions are:

1. Does a toddler HAVE to be potty training to wear pull ups or can I use them in place of diapers?

2. Is it too soon for pull ups if hes only 15 months and not potty training?

3. Anyone who has used pull ups, do they work well?

Thanks ladies! Here's my little June Bug💙