Thank you @jerrysievert. I had already been faced to those issues. API changes doesn't really matter unless you want to keep running behind Google V8 team and there dreams about JS implementation and tuning.
In the other hand, I totally agree with. the build requirement is a mess and not everyone may have the nerves and passion to build V8. That's way I provide a small piece of shell script to build v8 locally as well as pre-built static library stored in an Amazon S3.
I'm not sure about what you're talking about. But here, if you didn't get the idea, is a MySQL plugin to execute JS script inside database. It's helpful for sort of task that seem to be tedious for SQL; like creating small CRC algorithm, advanced JSON manipulation/lookup...
My motivation behind is: simplify SQL queries by delegating all expensive calculation to Javascript layer.
I found the great use-case is when mixing JS with Trigger.
it will depend on what's kind of project. if it's a widely used product: kind of mobile app general public, try base your compagbe on twitter and facebook. buy sponsored ads.
-be active on social media.
-invite friends and familly to use and invite their inner circle.
-reply on users feedbacks and try to satisfy them.