Wilkins, Francis, Keegan, Platt, Souness, Waddle, Hoddle, Hughes, Aldridge, Lee (Sammy), Hateley, Robinson, and even our Mick McCarthy are some that I can think of who went and played for a European club during the 80s, plus Rush and Lineker as you say. Admittedly not all English.
As far as I am aware, we have relegation clauses written into most of the contracts. That also goes against us when we are trying to attract new players - even though it is the correct thing to do. I wonder how many of our championship rivals can say the same.
There doesn't need to be a salary cap imo. A club should be allowed to spend more if it has more, it encourages good business. What does need to change though is a complete end to installments. If you want a player then you pay up front today. No clauses where you have to pay more if the player reaches X amount of games etc either. Things need to be kept simpler where clubs can't end up with huge unexpected debt.