Hi Hybride!
Well, after playing a hybrid int char for over 1 year now I think I can give you at least some hints and tips.
Basically there are 2 types of int hybrids, spear or sword and shield.
Spear is doing more dmg therefor faster lvling while sword/shield gives you a significant boost in defense which can be essential when fighting higher lvl mobs, uniques or pvp 1vs2.
Both builds have proven to be quite strong and fun to play, the difficult part is to get the right balance. In general for sword/spear you should aim for a higher mag balance than for a spear build.
If you can't really decide which to chose, dual weapon might be an option as well meaning you take both sword and spear skills and just use the weapon that fits best in the current situation.
Takes some practice and some more sp but in my opinion it's lot's of fun to play.
As you can probably see, there is no best build cuz all got advantages and disadvantages therefor you should just go for the build that you think fits you best. Just go (if you havent already done so) through the first 2 or 3 pages of the characters and skills section of this forum and look out for hybrid int / spear / sword threads so you can make up your own opinion.
Regarding the question which server to chose... I can't help you with that one. Only have played on Babel and a bit on Sparta (lvl 19 xD) so not much experience there.
I hope that helped you a bit, if you got more questions just post them if you can't find the answer in the guides or tutorials.
Have fun playing SRO and don't become too addicted to it
