Misc: Wha is the highest fence in the grand national?

Questions

judge dredd, future law enforcer, judges over which city?

who has a record 5 wins in f-1 racing?

who has the most wins in 500cc grand prix racing, with 8 wins?

at the f-1 grand prix race which killed aryton senna, which other driver suffered the same cruel fate?

the top ranking title in sumo wrestling is known as?