For (1), the answer right now is no. Once the dead node detection occurs, NameNode will swiftly act at re-replicating the identified lost replicas. There's something along the lines of what you need being worked upon upstream via https://issues.apache.org/jira/browse/HDFS-7877 but the work is still in progress and will only arrive in a future undetermined CDH release.
For (2), you can hunt such files with replication factor of 1 and raise them to 2 and wait for under-replication count to reach 0 before you take the DN down. The change of replication factor is doable by the command 'hadoop fs -setrep'.