I have 7-node hbase cluster (6 regionservers/hdfs nodes, 1 master), with one big table containing 500M+ entries.

It's a heavy-write light-read database.

1. Is it okay that the table has 1000+ regions for 6 regionservers only? 

2. Is it okay that one regionserver is 10x as loaded as others? See http://michal.medvecky.net/rs.png . This is a constant state, not random.
Row keys are random, not sequential. 

3. Is it okay that index table has 1000+ regions as well?

The problem is that I need to speed up writes and it does not seem that adding node helps. 

I'm using hbase 1.1.3 + phoenix 4.6.0 on hadoop 2.7.1 on Ubuntu 14.04.

Thank you