1 Can a medic use his ability if down?
The following answers are for Bolt Action Second Edition
Yes. A friendly infantry/artillery unit only needs to be within 6". Note that this includes the medic unit itself.
2 Can a commander use his ability if down? We played he could use his command bonus but not the extra orders, as he needs to be given an order to then order others.
No. See page 83, "You Men, Snap to Action!" for more details.
However, his morale bonus still applies even when the officer is down. A friendly unit only needs to be within 6" (or 12"). Note that this includes the officer unit itself.
3 How far into a wood can you see? The reason for this question was I had two units with Recon so they moved to edge of woods fired at enemy and when attacked retreated into woods.
Remember, it is up to the players to decide how the terrain works in their game. This must be agree upon before the game starts. That being said, you can see into the woods. However, see "Dense Terrain" on page 52. For a large wooded area, using several patches of "Dense Terrain" would represent restricted visibility.
4 Fubar if friendily fire do you still count pinned modifiers for unit.
It is handled like any other shooting. All the to hit modifiers on page 54 apply. This includes, "Per pin marker on the firer".