After I finish this IWD run, I'm thinking of doing an IWD2 run, also with an NPC mod for extra banter and whatnot. The details can be found right here, but the short version is that these are my options:

Diriel, a Neutral Evil Elven Druid Male (A Romantic Option for the Elven Female PC)
Hildury, a Chaotic Good Half-Orc Barbarian Female
Jaemal, a Neutral Good Aasimar Sorcerer Male (A Romantic Option for a Male or Female PC)
Nikosh Bracegirdle, a True Neutral Halfling Rogue Male
(Sir) Wind Nord, a Lawful Good Human Paladin Male
Peony, a Chaotic Neutral Gnome Wizard-Illusionist Female (A Romantic Option for a Male PC)
Prachi, a Lawful Neutral Human Monk Female
Rizdaer, a Lawful Evil Drow Fighter Male (A Romantic Option for a Female PC)
Salomeya, a Chaotic Evil Half-Elven Bard Female (A Romantic Option for a Male PC)
Valeero, a Neutral Good Human Priestess of Lathander Female

Also, the mod only works right if the PC is in the front slot. Therefore, the PC needs to be both a tank and a party leader. On top of that, I'm really not a fan of multiclassing in 3e D&D, so I plan to keep everyone single classed. All that being said:

1) What build would you recommend for the PC?
2) Which NPCs would you recommend I take with me?

Thanks.

Avoid paladin because they refuse to take rewards and do other things. Monks aren't recommended either because of their relatively low damage output .

Most of time you can choose which party member does the talking, therefore a party leader with non-existent diplomatic skill is acceptable.

Assuming you don't want to lower any stat below 8 for cosmetic reasons I recommend a dwarf barbarian as leader with stats 18-14-20-8-8-8 (or half-orc with 20-14-16), raise only strength at level up.

Add the following:

Rogue (the only one to handle traps and locks, pump up strength)
Priestess
Bard (to let the other characters shine)
Druid
Sorcerer

With your restrictions, your PC is going to have to be either a fighter, barbie or a cleric then. If you were willing to add 4 fighters levels to another class, you would have more options for a front liner.

Considering what you've said, I would go with a human fighter. My stats would be 18-14-18-13-10-3. Dialog options don't play much of a factor in the game and characters don't always start dialog with the party member in the first slot anyways, so I'd just forget about conversation skills for your PC. If you frown on mix/maxing, then go for 18-14-18-8-10-8. The 13 int in the first build is for the expertise feat, however if you're against min/maxing, you may have to forgo expertise altogether. Finally, the reason I would take a fighter over a barb is barbs don't get many feats or weapon specialization.

Although, I wouldn't take a barbie, Kmonster's barbie builds are also fine but I don't like putting WIS below 10 on any character. But of course, in the end, it's your call.

For characters, I would add the following:

Pally or barbie (I prefer at least 2 heavy hitters in my parties)
Priestess (If she can mix up melee and ranged when needed)
Rogue (use slings and/or thrown weapons, boost STR)
Bard
Sorceror