Paras - I'd seen them stuck just outside the perimeter of the field (they were just south of a runway at the time I saw this happen). Others online at that time indicated they have to be released within VH distance of the field, but I've never tested this.
Torps - Try under 200 kts, and under 200 alt.
Skins - It's been mentioned in other posts, but I don't recall if anyone from HTC spoke about it.
Cheers