Newbie RV questions

[TheBigRedOne]

1) Does the number in the "cross" mean the causalities suffered?
I sometimes see them hit where a unit isn't, but I see a number showup.
I am guessing it is the effect of the radius blast.

This is correct. It is the number of casualties inflicted.

2) Upper left corner unit. Does the "H" stand for "Heavy gun or equipment"?

Yes.

3) Is there a "key" to give you an idea of the amount of damage you could
inflict on a unit before you shot? Like a percent to hit etc...?

Short answer, not really. Using data like the PEN or Lethality values along with the defensive values, as well as distance from target, range of your weapons, etc, you can have an idea how successful a shot might be, but there are no hard-and-fast % associated with this.

4) How do you figure out how much travel points you could be using to
move into or thru a hex? The manual tell you to use "F2", but then do I
need to manually figure out in my head what it is going to take to get from
A to B hexes?

There is a 'view reachable hexes' setting in the task-bar and within the drop-down menu. I use it a lot when it comes to movement. There's also one for visible hexes, spotted units and units that can be targeted. It takes a bit of time to toggle through them, but it is worth the time when planning your turn.