Like somebody said You should hire professional, you have misconfigured Apache and Mysql. Apache spawns too many processes and Mysql is not caching properly. WTF is that your cache limit is higher than your query size? 30 QPS is really low, ATOM 270 can handle that with ease and with 20% load. With similar xeon i had 120 QPS and I never had database error.
And you do not need to use mysql persistent links, I do not use it and my avg. connection is 10 max 47.
With similar setup (Xeon 3060 and 2GB of ram) I had more than 700 people online with 10 other sites and load avg. was in range of 0.5-1.5.
Please post output of this commands:
free -m
when site is under heavy load vmstat 3 and iostat
Thanks