I'm a new writer and so still learning but feel that I am fairly good at grammatical and spelling as well as visualizing scenes. Check my bio for more details. I have been involved in swinging, group sex, partying, threesomes, anal, etc. and can offer advice in that regard.
The stories I have written to date have been influenced by things I've seen or done in the party scene or swinging as 'straights' know it, so possibly can help you with stories in that vein. My stories tend to be very explicit but hopefully not crude, IMHO. The things I write lean towards stroke material and I don't see 'Gone With The Wind' or 'The Old Man and the Sea' in my future.