Nail trimmers are in my opinion a matter of personal preference. It is also a good idea to keep a blood-stop powder on hand just in case you cut one a little too short
Defiantly get your dogs nails clipped if they are catching on things
Nails should be short enought that when your dog stands, the nails do not touch the ground or make noise!! It is a good idea to trim every two weeks, especially if the nails are long now...it may take time to get them back down to where they need to be.