Definitely the FEL hooks. Are you asking what the dealer should throw in for free, or what you should purchase additionally? Free delivery's nice. Beyond that, I don't really expect to get free things when I buy something. My dealer put the hooks on me for no charge, and even painted them orange. I was grateful for that and wouldn't have minded paying, since it saved me the cost of a welder (so far).
As for what to get, if that's what you're asking, make sure you want to spend the money for the MMM. Personally, I can't see myself ever mowing my lawn with a tractor that I typically have a FEL and a backhoe on. I have 1990ish John Deere LX176 lawn tractor. I go out, start it, cut the grass, and put it away. It serves its purpose, and I ask nothing more of it. When that dies, I'll pick up whatever I find on Ebay or Craigs List for $300.
For the cost of the MMM, you could get something much more useful, imo. Of course, less than an acre of my property is grass, so I might have a different opinion if I were mowing four acres of grass every week. But then again, with the R4s, I don't really have much grass left to mow anyway.
Congratulations on your purchase, btw! You'll love it!