The following is to the best of my knowledge. Take with whatever grains of salt you want.
1) Classes: is the difference between the 50% and the 60% DP limit that heavy? (I just tried to make two 1st lv characters, so probably it's clearly heavier at higher levels)
Yes it is. For many classes 50% of your DP will normally be spent in attack and defence, so this leaves either 0 (if 50%) or 10% DP (with 60%) to spend on Ki and MK. For Mentalists and Wizards the maximum percentage determines how high their Projection can be, as that they can use 1/2 their max in it. For starters.
2) Materials: this might be a really dumb question but.. as per page 51 "obtaining a better result with materials with a negative modifier is more difficult". Does this mean that the star metal (difficulty +80) is incredibly easy to shape?
Yes, yes it is. Good luck getting any though.
3) Round, Movement and Actions: a round is just 3secs long...It's a little odd to me, as (if i intended well) a really fast character (AG/DEX 10) could run 115 feet, then making others 3 actions (including multiple attacks) just taking an increasing penalty. Did i get it wrong? If not, is there a way to increase the lenght of a round without unbalancing the game (spell duration an so on)?
No, that would be correct, but then time has always been a problem with these games. There might be ways to change this, but it would be really complicated. I suggest trying not to worry about it.
4) The Combat Turn: depending on the intentions of the characters/pngs, the combat order might change. Do the players have to plan everything in advance? What if a wizard decides to cast an offensive spell to a far enemy (getting a +20 initiative) and the target is slained before his turn? Will the player be able to change and attack another enemy (lets say,with a staff), just decreasing the initiative?
No, They do not have to choose everything but they do have to choose some things. For example, in the above, they could not change how they plan to make the attack (a spell), but they could choose not to attack, change target of the spell, change which spell will be cast (with some exceptions), etc. As long as it would not change their initiative. As such they could not Draw a weapon, or attack with anything other than Unarmed and Spells.
5) Criticals: I really like the high number of locations but, is it possible to lose just an eye (and not the whole head
Yes, with an aimed attack you can. With a normal critical I think your going to go through the eye to the brain...
6) Ki Techs: how do I calculate the secondary cost? Attack bonus +10, for example, cost 4 as secondary effect. Optional char: Ag+2, Pow+2, Will+3, Strenght+2. I could pay 6 (4+2)Ag, or 4 (2+2)Ag AND 4 (2+2)Pow, right?
Yes you could, or you could put it in its basic stat (which I believe is DEX. This allows you to pay just 4DEX, 6 from (2)DEX + (2+2)AGI, or 8 from (2)DEX + (1+2)AGI + (1+2)POW.
7) Summoning: from what i see in the monster compendium, almost everything (natural creatures, undeads, constructs, supernatural monsters ecc..) can be summoned. Is it correct? Could someone summon a horse? What are the seals of invocation? Does the Control ability work only on summoned creatures?
No you can not summon a Horse. Undead and Natural Creatures cannot be summoned, Beings Between Worlds and Spirits can be summoned. Undead are special, as they can only be summoned by other Undead. Natural Creatures are natural and thus cannot be summoned in any way.
Seals of Invocation are Ki Summoning from Dominus Exxet.
Diseases: pag 216 "diseases might be the ones listed in this chapter"..where's the list?
Um...Thats a good question, anyone know?
9) Monters Creation (last one, I swear!!
): some spells allow you to create creatures. Is it true that they can't know any spell unknown to you, or do they just have to share your magic paths? If a spell description says "you can create a total of X presence in creatures"..how do I calculate the presence of a creature in the books? Last but not least..can a creator (Dm included
) choose the size of the monster freely, wothout paying extra DP's?
1) You must know the spell to give them the spell innately. However, after they are created they can learn any spell as normal for a creature of their INT.
2) Presence is based on DP I believe. I think that their Presence is equal to 1/20th their DP (so every 100DP is 5 Presence), at 600DP (level 1) you have Presence 30. I could be wrong.
3) Insofar as I know there is no 'price' for increasing or decreasing in size, however size is based on CON and STR, so you have to pay for their stats.