Ok, I'll tackle the "hair pad". I've asked around. A lot. And none of the fashion historians I know (that focus in that era) have ever heard of such a thing. The term hair pad will bring up a lot of results in searches, but that's because it's the term used for any shaped pad used on the head to augment hair (like a bump-it, but a small pillow). I do also know of the existence of merkins, but that's for a different region. Not only does the ability to stick a pad of hair in an area that would sweat too much for any adherent to work make this nearly impossible, but there's no evidence I've ever seen for this to be something considered specifically attractive. Women's garments were very rarely sleeveless at this time, their undergarments even being sleeved to help with absorption of sweat and ick. So, it's certainly not something that could be fashionably worn, only very privately. I've read some pretty in depth daily journals written by men in the 18th and 19th century (Walter's Secret Life, Samuel Pepys diary, etc) and despite mentioning very specific things they or others find attractive (Walter is very NSFW), I've never heard of this.

Follow-up question: why have Regency romance novels as a sub-genre been generally dominated by female authoresses since their inception, rather than males, or a mixture?