not fixed, but not as bad as pes 2013. however this may appear amplified to an extent due to the player awareness being truly awful (on manual & semi-assist)
depends what specific situations you refer to: when you pass to a player can you move the receiver freely? no; when the computer plays a through and you try and block it out? yes.
there will always be rails to an extent otherwise it would just be a bunch of retards fumbling around the pitch as they attempt to move into the ball precisely. for me the demo feels fine in this regard.
i tested this.
i ran only with dante for the first half and he was completely drained of stamina, the rest of the team had around 1/2. in the second half i ran with only boateng and his stamina drained to zero, the rest of the team (barring dante) had around 1/4 remaining -- bear in mind only these 2 players really touched the ball at all, so the rest of the team really shouldnt be that low on stamina, however, this is a marked improvement over pes 2013 as that game was pretty much solely based on time on the pitch.
and lastly:
no. imo pes 2013 was 40% complete, but that 40% was rather good (mainly the passing game), however the missing 60% was too much to handle (online modes, air passing, physical side of the game).
pes 2014 demo feels like it is 65% complete, and that 65% is also very good, but 35% of the game is buggy or broken and that is what's stopping it from having "that" feeling. at this point it feels like a very solid base rather than the finished article (unless that 35% is fixed... we'll see when the official demo releases

)