You should set up one server as the master, and direct all writes to it, and configure as many slaves as you have the money and rackspace for, distributing the reads among the master and the slaves. You can also start the slaves with --skip-bdb, --low-priority-updates and --delay-key-write-for-all-tables to get speed improvements for the slave. In this case the slave will use non-transactional MyISAM tables instead of BDB tables to get more speed.
mysqldump -h mysqlhost -u username -p mydatabasename > dbdump.sql
As unique integers representing the powers of two, due to storage optimizations.
SHOW INDEX FROM techinterviews_questions;
SELECT COUNT (user_id) FROM users would only return the number of user_id's.