The warhead is the same weight. It is HEAT, as are some variants of the Hellfire - same warhead I think. A frag could be fitted. The range is significantly greater.
Yes, very much so, just not on a helicopter. It is however likely to be a good fit, you'll see why (it will look very familiar).:D
https://en.wikipedia.org/wiki/Brimstone_(missile)
It's also been extensively tested on Reapers.
It never ends.
http://www.dailymail.co.uk/news/article-3639878/Policeman-stabbed-death-outside-Paris-home-attacker-holding-officer-s-wife-son-hostage.html?ITO=1490
"...The mission data files (MDFs) generated in the U.S. labs are sensitive because they are essential to the aircraft’s stealth characteristics. They include information that allows onboard software to build a so-called “blue line” flightpath that avoids exposing its less-stealthy viewing angles to hostile radar. This process is based on a highly detailed model of the aircraft’s radar cross-section against all known threats and at all aspect angles.
The MDFs also include target models that the sensor system uses to fuse radar, passive electronic and electro-optical signals into a single set of target tracks...."
https://news.vice.com/article/what-is-the-pentagons-multi-billion-f-35-jet-actually-supposed-to-do-1