2. Is there a synergy effect implemented or planned ?
http://www.d20srd.org/srd/skills/knowledge.htm
Synergy
If you have 5 or more ranks in Knowledge (arcana), you get a +2 bonus on Spellcraft checks.
If you have 5 or more ranks in Knowledge (architecture and engineering), you get a +2 bonus on Search checks made to find secret doors or hidden compartments.
If you have 5 or more ranks in Knowledge (geography), you get a +2 bonus on Survival checks made to keep from getting lost or to avoid natural hazards.
If you have 5 or more ranks in Knowledge (history), you get a +2 bonus on bardic knowledge checks.
If you have 5 or more ranks in Knowledge (local), you get a +2 bonus on Gather Information checks.
If you have 5 or more ranks in Knowledge (nature), you get a +2 bonus on Survival checks made in aboveground natural environments (aquatic, desert, forest, hill, marsh, mountains, or plains).
If you have 5 or more ranks in Knowledge (nobility and royalty), you get a +2 bonus on Diplomacy checks.
If you have 5 or more ranks in Knowledge (religion), you get a +2 bonus on turning checks against undead.
If you have 5 or more ranks in Knowledge (the planes), you get a +2 bonus on Survival checks made while on other planes.
If you have 5 or more ranks in Knowledge (dungeoneering), you get a +2 bonus on Survival checks made while underground.
If you have 5 or more ranks in Survival, you get a +2 bonus on Knowledge (nature) checks.