Yes. At the very least, he could go prone.Question said:Can he full attack then duck under to gain total cover/concealment(not sure which either)?
Standing up from prone is a MEA (or DC 35 Tumble check per CAdv/Epic).Question said:What about straightening back up?
In the table of combat modifiers, the condition of kneeling or sitting is mentioned. (It grants +2 AC vs. ranged attacks, and -2 vs. melee, so it's literally a kind of "half prone" condition.)
Here you go:Question said:Also can someone explain the difference between cover/concealmeant? If a wall is at my waist height, do i have cover, concealmeant, or BOTH?
SRD-Combat said:Low Obstacles and Cover: A low obstacle (such as a wall no higher than half your height) provides cover, but only to creatures within 30 feet (6 squares) of it. The attacker can ignore the cover if he’s closer to the obstacle than his target.
starwed said:In the table of combat modifiers, the condition of kneeling or sitting is mentioned. (It grants +2 AC vs. ranged attacks, and -2 vs. melee, so it's literally a kind of "half prone" condition.)
Unfortunately, it's not really mentioned anywhere how you move into or out of this condition. (Could be wrong on this part.)

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.