A passport is an official picture ID issued by your home country. It is also proof of citizenship. A Visa is a preliminary entry permit into another country. It can be viewed as an invitation to join a party, it is however no guarantee that you will get in. Quite a few people have been turned around although their visa request was approved.

The CA RSOL site is chock full of Travel related issues.
http://californiarsol.org/2013/01/international-travel/
http://californiarsol.org/tag/international-travel/

This article / paper is a very good attempt at shedding some light on this.
http://californiarsol.org/2014/06/international-megans-law-rso-travel-issues/

It points out the difficulty of traveling to english speaking countries (US, Canada, UK, Ire, Aus, NZ). I do not recall anyone reporting on Ireland specifically but I would proceed with caution.

Another thing to be careful about is the advanced notification requirement in AWA states. I see no mechanism or requirement to report to foreign police while in another country.

I thought I remembered a page on the topic on http://www.oncefallen.com but I cannot find it now.

Found it
http://www.oncefallen.com/travel.html

From what I understand (and be aware I really know nothing specific about it) but the homeland security sent some type of notification to countries recently alerting them to RSOs that have passports and how to find the info on their own. This letter specifically says that these people are traveling to other countries to participate in criminal activity and trafficking - since that happened I understand that most countries are refusing entry to USA RSOs - I would like some first hand info on this also

Canada has direct access to US criminal records. They will deny entry to anyone with a criminal record (including decades old DUIs and such).

For RSO specific travel to other countries, yes, the US government will generate a "green notice" and forward it to Interpol, which in turn notifies the visiting country. It is then up to the visiting country to take action or not. This is all done on the down low and the exact content of these notices is not known, but it appears that it includes reference to the sex crime conviction (seems only for those currently required to register) in addition to language that the individual is likely to repeat such crime.

Some countries will then deny entry to the traveling registrant based on this notice, and some won't. It is up to each country to decide who to let beyond their borders, as well it should be. The more the country depends on the US for whatever the more inclined they are to play along. Sound like most South / Central American countries, the English speaking countries, sex tourism (in general) destinations (Phi, Thailand, etc), will deny entry. No explanation, no appeal, buy a full fare ticket and go right back.

Since the US Government cannot restrict travel outright, this is the next best thing for essentially imprisoning RSOs in the US. Which is bizarre, because now all these 'horrible' people will spend their time and vacations domestically, alongside precious American and possible scantily clad children, at US beaches and such.

Everything I know is on the web sites linked. There are first hand travel accounts, and there are a lot. This practice is also trudging along in the US Congress under "International Megan's Law".

Do you need a passport to drive into Canada?

Do they run a check based on your license if not? Is it by name?

What if your last name changed and you've no social on your license can they still see your history?

Canada has linked with USA criminal data base, so they have all the information. You still required to have passport or pass card to travel to Canada. So once you arrive at the border check, they will swipe the card/passport to get information. They reject people with any criminal history. That's what I read from their immigration website.

If you want to go to Canada and have any background at all, you will need to contact the nearest embassy and talk to them. Expect it to take 60-90 days to get a decision, so don't wait till the last minute.