I dry hop in primary all the time and I use whole leaf hops and I just throw them in and have no issues with racking or with my auto siphon. You can simply put them in the carboy slowly by hand. First wash your hands well and rinse well and dry with clean towel. Whole leafs can be a pain in a carboy cause you have to do them slowly. (I use buckets, cheap and easy to clean, seal well and are easy for an old man like me to move on a cart.) Amount to use will depend on you and what your looking for. In my IPA's I have used up two ounces. Amber ales not so much but it is your beer use what you want. Let it sit for 7 days before packaging -- well that is what I like to do.