I'm confused re the Mentor Lines score. Here is an example of one output (3 best moves selected):

Time Depth Score Positions Moves
0:45 2/9 0.06 5078087 5...Nb4 6.d6 Nbd5 7.d4 Bxd6 8.dxe5
Bxe5 9.Nf3 Bg4 10.O-O
0:19 2/9 0.07 2127053 5...Na5 6.Bb5+ Bd7 7.Qe2 Be7 8.Nc3
O-O 9.O-O c6 10.dxc6 Nxc6 11.Bxc6
Bxc6 12.Qxe5
0:22 2/9 0.16 2471784 5...Nd4 6.c3 b5 7.Bf1 Nxd5 8.cxd4
Qxg5 9.Bxb5+ Bd7 10.Bxd7+ Kxd7

Minimized, on the top of the Mentor Lines window, the following is shown:

....Nd4 6.d6 Bxd6 7.Nxf7

1. Since 5...Nd4 etc. has a score of 0.16 versus the other two moves with 0.06 and 0.07, is it correct to assume that the highest score shown in the best move? Does the score have anything to do with the other moves shown in 5...Nd4, i.e., do all those moves have to be played in order to reach the score shown?

2. Sometimes,when minimized, the first move shown on the top of the Mentor Lines window is different than the highest scoring move in the window maximized......why is that?

3. I assume that the above scores the best move whereas in the analysis window, after running an analysis, the score shown indicates whether black or white is ahead (positive for white ahead, negative for blask ahead).....correct?

Thanks for any clarification you can give me.

Be careful.
I have notice that the move show in the minimize window is not necessary the best move.
Look at this position (anderson problem in the nunn's enigms, academy section):
Black: King b5, Pawn c6 c3 and f7, Tower g3, Bishop h2.
White: King c7, Queen e7, Tower a3 and b1, Bishop b3.
Mate in 2.
Put this position and look at the move show in the MINIMIZED window of mentor: this a mate in 3:
1.Fc2+ Rc4 2.Tb4+ Rd5 3.Dd6#

Now MAXIMISED the mentor window and you can see that the deep analyse find easily the mate in 2:
Temps Profondeur Score Positions Coups
0:00 1/3 Mate03 4018 1.Fc2+ Rc4 2.Tb4+ Rd5 3.Dd6#
0:00 2/4 Mate03 6168 1.Fc2+ Rc4 2.Tb4+ Rd5 3.Dd6#
0:00 2/4 Mate02 9659 1.Rd6 Fxb1 2.Db7#
0:00 2/5 Mate02 10931 1.Rd6 Fxb1 2.Db7#
0:00 2/6 Mate02 18626 1.Rd6 Fxb1 2.Db7#
0:00 3/7 Mate02 28171 1.Rd6 Fxb1 2.Db7#

Conclusion: in the minimized window you have the move with the highest score but not necesary the best move.
In fact, i think that frequently the depth analyse of the best score move is not enough. The best score move is frequently the first good move that the mentor analyse found (with little bit seconds of analysis time), but if you let more time to the mentor, he found new good moves with more positions analysed (here 9659 positions) and better depth. Often, those new good moves haven't got the highest score (because the mentor go more deeper in the position) but are the best moves!!!
Probably, if the mentor had spent more time on the highest score move, he will change the score!
I'm not very sure about this, but i think that in order to have the best conclusion when you search the best move in a position is to look in the maximized window and keep the move that have the more long time of analyse, the better depth and the more positions analysed (the move at the bottom)
Try it when you play a game, look at the move show in the minimized window, maximized it and let time to the mentor to find new good moves, frequently, those new moves have not the better score but are better moves.
If my conclusion is good, i hope that it will change in the next chessmaster.
What do you think about this? (sorry for my bad english!)

Seems that you are somewhat correct. The minimized Mentor Lines moves appear to be the first "best" analysis and this never changes even though the maximized window moves do change as the program digs deeper. And I have noticed that on occasion the minimized moves are not always the highest scoring moves. Perhaps I'm wrong but thought I'd post anyway.