Noob Question (Sorry)

So apologies in advance because I haven't played tabletop in about 17 years, I'm thinking about getting back into the hobby and bought the CSM codex last week to plan an army, but I have a couple questions.

So I want the centerpiece of my army to be a chaos lord + MoE + 10 Chosen transported by a Rhino.

My main question is will the Chosen ability (This unit is eligible to shoot and declare a charge in a turn in which it Advanced or Fell Back.) also apply when there are leaders attached that do not have the same ability?

Second question, if I'm playing the veterans of the long war detachment, can I apply two enhancements (Warmasters Gift to the Chaos Lord, and either Eye of Abaddon or Mark of Legend to the MoE) if they're both part of the same unit?

Finally, is putting this many points into a single infantry unit tactically sound or a terrible idea on the tabletop?