Concerning TestComplete 12.50 with Chrome version 66, there's another thread up here that gave feedback from the actual customer service staff that, at this time, recommendation is to downgrade Chrome to version 65 as there are issues with v66 that need to be addressed. If you need to address this further, the best suggestion is to contact support directly at https://support.smartbear.com/message/?prod=TestComplete
As for your other problems.... If you want us to try and answer them here on the forums, please create additional queries/posts for each with as much detail as possible and we'll do our best. We may end up, at the end, referencing you to support but we may still be able to give insight.