I wish I could just change the title to IFR questions as I'm finding a few more.

1.Can someone please help explain the difference between these two to me? I know the MOCA is minimum obstruction clearance which gives obstruction clearance and navaid reception for 22nm(from vor). Is that the difference between the two? The MORA gives no reception? Why would you use one over the other?

2.VORTAC tells me that a VOR has DME ability because of the TAC, even though the TACAN is for military use, correct?

3. (looking at Jepp enroute chart legend) Why do the charts show Class A? The sample I'm looking at is p61 of the Jepp introduction fyi. Just wondering why it would ever be changed from FL18-FL60

Thanks
Duck