Shadowknights are without a doubt the best soloer, bards are good, any petter can.
For dual boxing you will want one class to require little effort to be effective, A mage or necro whose pet can fight while you play the other toon, or a healer and another class so you only have to hit O to use heal on a standard target. Going say a rogue and a warrior is stupid because you can't play both effectively at once.
If you say went a Shadowknight and Necromancer you could tank and heals yourself while the necro sits there and pet fights speeding kills up and to pact you if you are getting hurt to much. Or you could make a healer and tank and target your tank and just press O when heal is down during a grind... Or you could make two petters and put them in some camp and go afk which I don't recomend because people do train afkers...
As for money...well one of the most reliable income sources I know are siloth rings... around level 40 you could solo them and get xp from kills and sell the rings for money...
Or you could farm for Crystalline orb in the goblin village south of halas... I don't think there is quite the market there used to be fore that fashion accessory as there used to be tho... At level 25+ it should be easy as cake to kill them.
To be honest unless you are a tank theres no point to getting anything other then basic gear until you are like 45+. The levels go by fast with boon and frankly there is no challenge, especially since it can be faster to level by killing mobs lower level then you quickly rather then go after mobs 3+ levels higher.
Edited, Oct 13th 2008 3:52am by SefanaPPO