As far as the free liveries, some of them will link you to AVSIM and you have to type down the search field.

No matter what system you have, I say to be fair will be a semi medium rig. You will be good using the default FSX airports with some 20% AI.
If you start using payware sceneries like FSDreamteam and some FlyTampa, you will get some frame rate hits.

At this point, the CS777 is flyable with some limitations that you have to deal with. I've done a complete flights already with it flying long hauls and landed manually. There is an issue with the ILS capturing on some of the airports that auto land will be an issue.
All of these issues and the other features out of the box will be delivered per CS, so we just have to wait when they are ready.

I know that there is another "777" product around the corner ready to be released. I've been flying PSS B777 version for years on my FS9. But I will tell you this CS777 will not go to the hangar, I will be doing hours of fun flying with this, no matter what.

Kin M.
(Klax)