Is it safe to travel when I am on my OPT-STEM?

This is an immigration question. Pass to that area.

Am I able to enter Toronto onb12/28/18? I got a DUI 19 years ago and have a misdemeanor for cultivation of marijuana.

This is a Canadian law question. Ask a Canadian lawyer, or one who practices with Canada. There should be a few available in Denver.

Is there any chances of rejection if i applied for a visa in canada for attending an event?

This is a Canadian law question. Talk to a Canadian lawyer. if you are in Seattle, there should be one handy.

Could someone who lived illegally in USA be able to get a work visa?

This is an immigration question. Pass to that area.

What happens if a company bills random people who have not been provided with their services on a grand scale?

You might want to check and see if they are registered in your state. If not, the agent for service for a civil suit would be the Secretary of...

Have them contact the US embassy and go about getting a visa.

There are too many questions and variables to answer these questions in a forum such as this. You need to consult and international lawyer who...

Can Indian citizen studying in Canada get F1 visa for US from Canada.

This is an immigration question. Pass to that area.

Can I travel multiple country's together?

That would depend on the Indian and Canadian authorities. I would contact the embassy/consulate of both of those countries and see what they say....

Which CC License do I want?

This is an intellectual property question, and should be in that area. I believe you need to consult an IP lawyer as to what choices you may have...