As for regularity of grooming, there are no set times. If your bird's nails are long, then consider what perches you're using or you can file them down.
Regarding clipping, I'd recommend you read:
https://parrotvolancy.com/should-i-clip-my-birds-wings/
I think Sailboat (not sure if him or another member) summed it up succinctly:
- precautions need to be taken for all situations if clipped or unclipped.
- you still need to take care of your bird's health; a flighted bird can exercise properly, but a clipped bird needs your help for wing flapping exercises.
Everybody has their own reasons for clipping or leaving flighted. A bird will not die because he has not been clipped (if that were the case, I dunno what's up with wild birds). That being said a clipped bird does not mean they cannot fly off or they won't get hurt (if fact, a grounded bird is more likely to get attacked, especially when lost but even at home, by ground creatures, such as cats, because they cannot fly away). In my area, clipped birds get lost and wind up being attacked by stray cats.
Take all safety precautions regardless of wings. Just because your bird is one or the other doesn't mean he is safe.