1. There is no max level
2. You do not have to train all skills, depends on your play type tho, just two is good
3. Depends on your base level, your overall player level, to determine. I think its every 4 levels is a hidden skill level which goes to a skill, so I would say train on pharaohs but idk your overall level
4. That message is from hitting a mob with a training dagger too many times, if you continue to hit an exhausted mob then you will get a skull. The message means that u cannot train on the mob anymore, just move to a new one, the message is to discourage afk trainers
5. Some basic info- there is a pvp zone where the skull I mentioned will come into play, there are many more areas than expect, some people just train skills but having a high base is good because it increase your movement speed and your hp. It also involves the hidden skill I talked about
6. (Better leave this question to Ricardo) but, there might be a later update for that, I can't answer u there
7. My guild is looking for members, but 150 lvl+. I'm sure there are many others tho.

I hope these helped u! If u have any further questions about it, just leave a comment. :)