I think many people on this board know that I love druid / fighter combos. If you dual, I personally recommend the totemic druid (his special ability is summoning things which is perfect when you need help kicking butt, and is also a very fast way of bringing in a friend).
The max level is 14 because in SoA, the experience cap is 2.9 million (roughly), so you can't reach the 3 million mark to hit level 15. Either way, Kaah is right that your first class can be a special kit, but the second class is always a generic one (Kensai -> thief, Assassin -> fighter, Berserker -> mage).
Since you do have ToB, install it now, as it won't affect you in SoA other than giving an extra map area and a new mage class (highly recommended). I'd recommend dualling your druid over around level 12 - you will have to be a level 13 fighter to reenable your druid side (until then, all spells and abilities are locked away) which can be a while, but when you do reenable to druid class as a fighter, you suddenly get back all your spells, with the full range of spell levels, including iron skins and insect plague (both fantastic!). The other advantage is that it only takes 300k of druid experience to hit that mark, which is pretty quick, and you don't "waste" a lot of experience points on your inactive class, helping you to start sooner on your primary (fighter) class. Fighter HLA's are often talked about here and are a fantastic way of making the toughest creatures die (whirlwind a dragon with 10 attacks a round and a fighter's THACO).
For weapons, since druids are limited, I'd recomend either dual wielding scimitars (there are a couple of +4 scimitars, and belm, +2, gives you an extra attack every round) or single wielding spears (you can get a +3 spear right in walkeen's promenade very early in the game, and later get a +6 spear, one of the few weapons that can hit through the best mantle spells that liches like to play with). Pros and cons of each, and to each their own.
Armor? Fighter / druids can wear anything and tank with the best (ask Jeheira) so +1 full plate, gloves, helm, whatever. You'll have a very nice AC, and can still cast to disrupt enemy mages, heal yourself, et al.
For the other classes, a Kensai/mage is nice (everyone here has tried one once) but I think a Kensai / thief is a better option - still great hitting, plus you can backstab with a fighter's thaco and easily start doing 50+ damage with a single hit (100+ is common, too). Added bonus: once the thief gets HLA's, choose Use Any Item to cancel out all the problems of Kensais, and then drop their AC some more and wear armor again and gloves, too.
Also, apparently, berserker/mages are a nice bonus, since they can use their rage ability to become immune to imprisonment and maze, so hang in longer against Kangaxx and other liches. Dualling katanas (for Zakkon's Derth Blade in the off-hand for extra spells) or singly using staves (there are tons of good staffs, including the staff of the magi (aka staff of cheese), and one of the few +6 weapons, are good ideas there.
Instead of a Berserker /cleric, I'd probably choose another druid, but clerics get some good spells that druids don't: holy smite (area affect with more damage as characters level up that won't damage your good or neutral party), and chaotic commands (make the target immune to charm-type spells) are some of the biggies that clerics get.
Anyways, I have to go back to work now.
N........
