No problem! You asking the questions forces me to double check how things work, like with player experience.
How do the players win experience? I've not been able to see anything on the rule section...
They win experience for the minutes they play? all the matches give them the same experience? or friendlies give less and cup give more?
(261872.2) - according to this, it was believed to be based on minutes played and your player would gain more experience in bigger games such as cup or NT.
(261872.3) - it was believed that roughly 1500 league minutes was enough to get an experience pop.
One thing that i cannot understand, is why one of my star players is rated so poor, is this one:
Should I fire him? His game was horrible the other day... and his salary is near double than the others...
Iturrao is a big (PF/C) so I wouldn't worry about comparing his ratings to Ataide. As a side note Iturrao is a decent big for a starting team, 7 in the four inside skills and some passing. Not as good as Yanes obviously but he'll make a good backup.
Regarding Ataide and Cordera, OD does matter a lot in this game, so that is probably why BM rates Cordera better. However, the context matters. For example if you are playing Patient and have an elite scorer then Cordera is better suited for his defense, the elite scorer will take most of the shots. But if you have a team of Cordera's then it's going to be difficult to score.
When playing Patient I would use Ataide as the backup to Cividás. As you might have noticed, with Patient the best scorer (or player with the best match-up vs defender) takes most of the shots. Thus you need at least one great scorer on the team. Using Ataide in this way will mean you always have a good scorer on the court.
When playing Motion I would start Ataide despite the low OD, as the JS will be helpful. One thing you could do is switch defensive assignments - for example set him to play SG but defend PF. He has 7 ID and 5 RB so he would do ok there, and you get the benefit of his offensive skills at SG. Most of your trainees have 5 or 7 OD so will be happy to play PF on offense and switch to SG on defense.
I wouldn't worry about his performance last game, as it was just one game and shooting 6/12 FG is good. If you can hide him on defense at PF then he'll be a solid player for a new team.
I did fire one of my "stars" when starting out, as I tried to keep my salary low. But that was before the league consolidation so almost every team I played was a bot, which are easy to win against. I'd keep him for now as his salary isn't that expensive, and if you use him as above then I think you'll get some benefit.
This are my 6 players that I'll train, one of them (Maradona) was given to me with the initial players.
I think they are all fine trainees to start with. You may not make much profit on this first set of trainees, but you should make a bit once they are finished and more importantly you'll gain a lot of experience in how training players works. Your trainees also have different heights and different weaknesses, which is good as you'll see different progress and learn something from that as well.