QUOTE
+smth small
This would be a vey bad idea. Senka has reported a lot of problems recently, because of this *smth small*. If you want to play and not to debug your own game all the way, please strictly follow installation instructions without any deviations. It means Baldurdash v1.63 + TS v6.11 + NeJ2 v6.9.1 + patch v6.9.2. In case of this installation or its variations (see the pinned topic), I'll provide you with technical assistance. However, if you add *smth small*, you'll be on your own.
With respect to Leina, well, it's a good question. Actually, I don't know what's your preference. Choosing Leina means you'll not be able to side with Shadow Thieves. On the other hand, to join Sime, you'll have to ally with Aran. This is a primary choice. Further, kindly bear in mind that you'll reach Leina when your party is at level 12-14. She is a powerfull bard at this level, if you need one. You have an option romancing and flirting with her but her romance has not been completed yet.
In fact, I would divide your question into three parts:
1) What is my party in the first part of NeJ2?
2) What is my party in the second part of NeJ2?
3) What is my party in the third part of NeJ2?
Now, I can show you only my personal preferences.
1) PC (kensai, later dualled to a mage); Imoen (charming rogue); Shar-Teel; Hrothgar; Dar; Accalia.
2) PC (kensai/mage); Shar-Teel; Hrothgar; Dar; Melora; Leina.
3) PC (kensai/mage); Shar-Teel; Hrothgar; Dar; Imoen; Leina (or Taffic if I don't romance Leina).
Good luck!