1) Red Naught Sword is very popular for IB, especially since it naturally has fire element. And you can wear a shield since it's a one hand sword. You might have to max one handed sword mastery in order to get the full potential out of it though. Veteran sword seems to be pretty good too if you are chaining BB with IB. If you are soloing mostly, you can also consider making a sage just to slave endow you too (30 minute endows).
2) IB is mainly affected by STR.
3) 2H swords tend to have higher ATK than spears, but if you uses a spear on a dragon with dragon training maxed, spears should hit for 100% on all sizes whereas swords hit for 75%. So it depends on the situation. Also you will have to consider whether you want to use a 1 handed spear/sword or a 2 handed one. You might have to do some testing to see what gives you the most damage. calc.irowiki.org might give you a good rough idea too for "monster combat simulation".
4) It is possible to get both DB/IB yes. You won't be able to max Hundred Spears with both DB/IB maxed however (lvl 9 only), but it's possible to max Rune Mastery, DB, IB together. Most people tend to only master either DB or IB as their main AOE skill, but there are some benefits to maxing both (DB is fixed fire damage but IB can be neutral).
5) Peuz set seems to be pretty good if you are ctrl-clicking stuff for the autocasts. The extra ATK and damage to all monsters is not bad too. Do note it's pretty hard to flee high level monsters though, and flee won't help you when mobbing / AOE either. You can definitely use certain components of it and not the whole set though. Medal of Honor is nice for the damage, or you could use something with a mantis card. Most people tend to use a rideword hat for the SP leech, although it is very overrated and an Incubus Pet works much better. Rudolf is very good for soloing since carrots will heal a lot and are light too. For middle heagear there is robo eye, something with dark pinguicula card in it, black devil's mask as a couple of good options.
Seems I might have give you more information to think about or to experiment with, but if you just want a straightforward recommendation, go with red naught sword for IB/BB, or go DB build around 125-130.
6) Firelock is the best, but +9 is not cheap, so you can consider Matyr, Verit, Green Ferus too.
7) IB can't really one shot most monsters unless you got megs (maybe not even then). So you definitely have to be prepared to take a lot of damage.
Edited by kasshin, 28 April 2012 - 08:58 AM.