iBoxx TRS

I am looking into iBoxx TRS to get fast exposure to a diversified portfolio. I have a few questions and would be happy if someone could help me.

*) what happens if index members change? Do the index members also change in the “swap” or does the maturity of the underlying portfolio get smaller as time passes? Default, M&A, Rating Migration, etc.

*) do different maturities have different underlying portfolios?

*) is there an on-the-run/off-the-run swap?

*) How do you calculate the implied funding level?

*) How do you calculate the correct NAV?

*) (How) Does NAV differ with different maturities of the TRS?

*) How do you hedge against interest rate risk?

*) How do you hedge against Subordinated bonds in that TRS. You don’t want exposure towards that.