How can I monitor SSD endurance?
Install f.e. SMARTmontools, SMART is especially designed for monitoring hard drives, and these days it can monitor SSD parameter the manufactured decied aswell
Search for write cycles, power on hours, power on count.
Find out what flash chips you have in your SSD, find the specs for that chip, and get the average write cycles.
From my experience the SSDs did break only on controller issues, not on write cycles, where overprovisioning should take over and replace the broken ones with spares.
How can I optimize the the performance?
Align it to the size of the "sector" size of the chips, you can find that out via specs for your SSD.
Additionally (while true for older drives it might not be needed anymore)
you should not fully write the SSD as long as you have other options.
That way the garbage collection can work better.
I think that http://www.storagesearch.com/ssd.html has a lot of information you might want to read into, for a better understanding of SSDs Pros/Cons.