Interestingly, in that latest gameplay trailer Archer at about 0:43 asks 'Kimi watashi Master ka' or roughly 'You are my (feminine) Master huh'. Did he refer to himself as a woman?
As for the Servants, here's what I roughly have based on Google Chrome's poor translation abilities.
Saber: Women wearing red dress. Excellent sword skills, characterized by higher overall combat capabilities (nothing we didn't already know).
Archer: Bows and indirect. Good at ranged weapons and dual wielding. The rest of the translation is horrible, but might suggest that there's a mystery to Archer.
Caster (I think): Half animal apparently, with good senses and high intelligence. Rest can't be really understood but it seems to say something about miasma and possibly requiring strength for the Master to control her.
Lancer: Strangely enough it seems to say that Lancer is contracted to Rin, even though her picture is next to Archer. Beyond that Lancer is fast and uses spears.
For the guy who looks like he might be Assassin: I got nothing.
The rest seems to say that the game will have some kind of tournament, though this could be a mistranslation. You can level Servants or Masters up through training. I can't tell from this if it's turn-based or real time.