Hello all, I am new to 40k and have a couple questions about rules and how to play 40k. As a Fantasy player, some of the rules are getting confused for me.

I am playing as Eldar and played an Ork player today - it did not go well. It has led me to question some of our understanding of the rules. The situation that I was particularly unhappy with is that it didn't seem possible for me to stay away from the Orks, as they are just too fast, and once they get to me I was killed nearly instantly.

I am having trouble figuring out how to defend myself from close combat troops, as the power of my ranged weaponry does not seem to make up for my utter failure to stay alive in combat.

I am also confused about assaults. Is there no option like in fantasy to retreat from the assault or fire my weapons at the enemies charging me? Can I really get attacked by the whole mob of guys behind the front line of the enemy, and what can I do to prevent that from happening?

Can vehicles really just move around however they want, front, back, and sideways?

I'd appreciate any basic tactical and rules based advice people are willing to share.