Flying in other countries

Is it as easy to fly in countries like Kazakistan, Afghanistan,
Mongolia, Russia, Pakistan as it is in N America? Do I just fill out
the regular forms, get the visas and fly right in?

Assume I have a PPL (Canada) and an experimental category plane like
the CH 601 or 701.

I've seen that in many Soviet states, theres no avgas, just the A1 jet
fuel. For that reason I'd aim for the rotax engine in the zenith
aircraft and use high octane mogas. But other than the aircraft and
visa/passport paperwork, what else is different?

I have specifically those countries in mind, Kazakistan, Afghanistan,
Mongolia, Russia, Pakistan. Any experiences?