The first tool that comes to mind is Monit, it solves both questions 1 + 2.
As described on their website;
Monit can act if an error situation should occur, e.g.; if sendmail is not running, Monit can start sendmail again automatically or if apache is using too much resources (e.g. if a DoS attack is in progress) Monit can stop or restart apache and send you an alert message. Monit can also monitor process characteristics, such as; how much memory or cpu cycles a process is using.
Monit for being proactive + New Relic (Lite) for alerting is a lethal combo. 
Hope that covers your monitoring & alerting needs.
