mysql performance test
1) Although I prefer tcpdump myself I would ask what is the reason not to enable slow logs because it is not that big of an overhead. With reasonable thresholds it's actually very useful.

If you want to be super cautious you can safely enable it with a conservative long_query_time and slowly dropping it. The variable is dynamic so you can change it on the fly if you experience issues. Also depending on the flavor of your server (Percona for example) you may be able to set log_slow_rate_limit which was designed for exactly this purpose.

Another way to do it would be to use tcpdump which you can do on the server, on a shadow server (if your networking setup supports it) or on the application server as well. Then you can use pt-query-digest to extract the queries from it:

tcpdump -s 65535 -x -nn -q -tttt -i any -c 1000 port 3306 &gt; mysql.tcp.txt
pt-query-digest --type tcpdump mysql.tcp.txt


This is a very versatile solution so it's worth to get familiar with. 

More info can be found on https://www.percona.com/doc/percona-toolkit/2.2/pt-query-digest.html

2) This is just an assumption but there are many-many ways to execute/replay queries so I think that's the reason for the dropped support. 

3) If you have your queries you can also use percona playback, mysqlslap, sysbench or any other tools to execute them as you wish. If you want to write your own stress tool I have a web request playback code example which can give you some ideas.