Re: All that needed is...
There maybe no way to check SSL certificate with SNMP, but pretty much any monitoring software can to it - Nagios has a plugin. Templating is needed for devices (phisycal of virtual) - SSL certificate check is generic and device independent, no need to involve SNMP.
Log file problem is not actual SNMP - that's content not and event... Though again - nagios has plenty of plugins for that (yes, client install is probably required).
As for Windows, well - MS just had to do it their own way: no surprise here.