nothing found specific for Arduino.
No these devices are universal, most makers of them have never heard of the arduino.
Does SSR operates like a normal (electromechanic) relay?
No it uses a device called a Triac.
If I generate a PWM signal, can i connect it directly to the SSR in order to take control of the output signal (AC)?
No. Only some SSRs have phase angle control. Then it needs the PWM filtering before feeding it into the SSR. See this link all about PWM:-http://www.thebox.myzen.co.uk/Tutorial/PWM.html
Do you have a specification on controllers or link to ?
This link shows some:-http://uk.farnell.com/jsp/search/browse.jsp;jsessionid=WAHSKPFBJVUQWCQLCIPZNFQ?N=0&Ntk=gensearch_001&Ntt=SSR+phase+angle&Ntx=mode+matchallpartial&suggestions=false&ref=globalsearch&_requestid=717784
They are expensive because they will handle a lot of current. There are cheaper devices that handle less current. Depending where you are in the world look at your local electronics distributor.