As for the blood that exits his body: if the amount is slight it does not invalidate minor ablution, but if it is copious then the safer course is for him to repeat the prayer, because a number of scholars hold that profuse bleeding from a person breaks ablution. Repeating the prayer is therefore more prudent and removes him from the area of disagreement. Allah knows best.

Praying on an elevated surface
Question: Is it permissible to perform the prayer on something raised above the ground—such as a bed—when one doubts the purity of the floor and has no excuse like illness?
Answer: There is no objection to praying on an elevated place like a bed, provided it is pure and steady so that it does not shake or distract the worshipper. As long as it is firm and pure, there is no harm in praying on it, Allah willing.

Praying outside the mosque
Question: My companions and I arrived at the mosque at Maghrib time to pray but found it packed. Fearing that the time for Maghrib might end, we prayed on the pavement beside the mosque, level with the imam. We joined the congregation by listening to the loudspeaker, yet we could not see the rows. Afterward we were told that the prayer of one who cannot see the imam or the rows is invalid. If there is a barrier—such as a small street or a road opposite the mosque entrance—between the worshipper and the mosque, is our prayer still valid? Please advise us, and may Allah reward you abundantly.