Im not an expert with how rogues were back in the day, but i've had mine for a good while now.
1. Merciless strike and stealth at 5 are almost required in both pvp and pve. Max damage put out this way. Also gouge at 3 is good for both. Sometimes in dung, if for example healer lags out, rogue can gouge and stealth if hes fast enough. In pvp you can wait out dots with it.
After 5 merciless 5 stealth and 3 gouge rest of the points should be invested in experts. Either absolute reflexes or poison. If you want to go full dung build ricochet is also good to level, it can do good damage to mob groups. Dodge and kick are mostly useless in dung, and to be honest, nowadays also in pvp.
2. Ive never liked axes for dung, especially ones with no accu. I usually manage to outdamage axe rogues using sword+kris combination. Also remember that sacrificing some damage in accesories for mana regen increases your damage output in the long run.
3. With the current situation, rogues can be pretty good tanks. Absolute reflexes work good vs high damage bosses and mob groups. Life steal allows good tanking even with not high amped healers.
Just in general, for pve, remember to get accuracy over anything. Mobs have surprisingly high dodge. You could miss over 50 times per termi run. Thats alot of damage, which could make the differwnce between one and 2 stam.
Also don't be that rogue that has low def and rushes into mobs before healers are ready. You will die. If you're +10 and have pots then feel free.
Some other tips: Use stealth after every mob group, it adds almost 2k damage every group (counting increased poison tics). Needless to say it adds up during the dung.
1. When it comes to pvp merc strike shouldn't be 5 always, I'd rather use points either on kick in the back or dodge for extra survivability, for pve go for highest damage + high life steal so you can deal high damage plus heal yourself.
2. I'd go for axe + dagger, but yes dagger are better in pve.
3. Rogue character with decent gears can tank any bosses, and rogue is always wanted in dungeon for faster run, barb are for tanking bosses like swamp slug. My rogue with 4.2k defence can tank any boss, can tank lab too so it's not a problem.
this topic is the most updated about rogue http://forum.warspear-online.com/index.php/topic/49660-full-rogue-skill-mechanics-features/
this can help you build your skill. The other topic are bit outdated