How to debug replication/range

I am trying to evaluate the cockroach db fault tolerance and scalability.
I started a local 5 node cluster and created 3 tables with a few number of rows. After I killed one of the instance, I did observe the under replicated ranges eventually replicated to other nodes. The questions are:

  1. Where is the control knob to tune when a node is considered permanently lost, and its ranges distributed to other nodes?
  2. Is there a place where we could easily follow the range replica movement, other than the info log?
  3. I tried ‘cockroach debug range ls’ to understand the range configuration.
    cockroach debug range ls
    /Min-/System/tsd/cr.store.ranges.unavailable/1/10s/2017-03-01T19:00:00Z [1]
    0: node-id=1 store-id=1
    1: node-id=2 store-id=2
    2: node-id=5 store-id=5
    3: node-id=4 store-id=4
    4: node-id=3 store-id=3
    /System/tsd/cr.store.ranges.unavailable/1/10s/2017-03-01T19:00:00Z-/System/tsd/cr.store.valcount/5/10s/2017-03-01T20:00:00Z [41]
    0: node-id=1 store-id=1
    1: node-id=2 store-id=2
    2: node-id=5 store-id=5
    3: node-id=4 store-id=4
    4: node-id=3 store-id=3
    /System/tsd/cr.store.valcount/5/10s/2017-03-01T20:00:00Z-/Table/0 [7]
    0: node-id=1 store-id=1
    1: node-id=2 store-id=2
    2: node-id=5 store-id=5
    3: node-id=4 store-id=4
    4: node-id=3 store-id=3
    /Table/0-/Table/11 [2]
    0: node-id=1 store-id=1
    1: node-id=2 store-id=2
    2: node-id=4 store-id=4
    3: node-id=5 store-id=5
    4: node-id=3 store-id=3
    /Table/11-/Table/12 [3]
    0: node-id=4 store-id=4
    1: node-id=2 store-id=2
    2: node-id=5 store-id=5
    3: node-id=1 store-id=1
    4: node-id=3 store-id=3
    /Table/12-/Table/13 [4]
    0: node-id=5 store-id=5
    1: node-id=2 store-id=2
    2: node-id=1 store-id=1
    3: node-id=4 store-id=4
    4: node-id=3 store-id=3
    /Table/13-/Table/14 [5]
    0: node-id=1 store-id=1
    1: node-id=4 store-id=4
    2: node-id=5 store-id=5
    3: node-id=2 store-id=2
    4: node-id=3 store-id=3

    How do I read this? For example, it’s not clear to me where the split point is, from ‘/Table/13-/Table/14 [5]’. Is there a way to dump the range key bound?
    I also tried ‘cockroach debug range-descriptors’, but looks like it does not work on an running instance (rocksdb instance LOCK hold).
    Thanks!