Urahara's zankpakuto is Benihime (Crimson Princess), his zankpakuto gives him the ability to manipulate blood while at the same time be able to fire energy blasts at level 9 and create a blood-mist shield. Kurotsuchi's zankpakuto is Ashisogi Jizou (Beast Killing) which allows him to paralyze enemies and make them feel pain than usual. His bankai, while not spoiling it completely, has an ability to manuever gaseous poisons. So, knowing this little information could possibly change your answers slightly, but we must consider how Benihime's bankai is unknown to us. In episodes 120-128 (current), Urahara mentioned that his bankai is not suited to train people or give them strength. We could obviously assume that his bankai should not be taken lightly of or underestimated.

Kurotsuchi, who has the ability to paralyze his enemies, may just stab him in the chest or nuts to attain victory. I'm sorry Mayuri, but it would take much more blood than that to beat Urahara. If Urahara were to be paralyzed, he would be smart enough to use his own blood or Mayuri's blood to protect himself from incoming attacks. This is all I know from few Bleach sites and episodes, so we will have to wait to see all of Urahara's abilites.

Now paying attention to the Uryuu and Renji fight, I have to say that Uryuu will win the fight. Excluding the fact that he is more intelligent, he also has amazing speed and ability to balance the amount of spiritual power he uses to unleash each bow. It all thanks to him that he took the risk of going past his own limits when using the Quincy accessory. For going past his limits, the Quincy accessory shattered and left Uryuu powerless once again. (The first time was when he faught Mayuri Kurotsuchi and used a certain technique) In later episodes, Uryuu meets someone who is able to bring back his powers.
Even though Renji has much more experience as a shinigami, he still has not mastered his Bankai yet, but still able to control it and win major battles.

Hopefully this is enough to keep the club going and I apologize that it is short. This time I want to see Kyouraku Shunsui/Ukitake Juushiro vs Yamamoto Genryuusai Shigekuni fight.