Thank you very much for your inputs, I'll try to follow-up and then ponder on the issue a bit more.
NotJabba: First, why choose short bow when you can use long bow? .... Second, why do just single-hand weapon specialization when you can use weapon + shield instead?
I see your point, however I personally perceive the long bow as a warfare weapon to be used at longer distances, whereas the short bow seems much better suited for the purposed of adventuring and close encounters. Therefore the reason behind this choice (and gamewise, there and more than enough bows to choose from).
The logic behind the single weapon proficiency for the cleric is very similar. Since the shields are likely hinder spellcasting of their users (although this is not reflected in the game rules in any way), it just feels more appropirate to leave a spell-dependent cleric unhindered in this respect, even for the sake of higher AC (and the corresponding in-game cons like spell interruption).
Hickory: Personally, I see an elven cleric as rather an oddity, both in lore and in game-play/mechanics. For starters, elves get bonuses to bows and swords, both of which a cleric cannot use. They also, typically, do not follow Helm, Lathander or Talos -- there are exceptions, yes I know. But on the whole, it seems like a very strange choice to me. But maybe that's the point, and why not choose that? Hmm. Something to think about.
I also feel a bit restrained by the available cleric kits and may eventually opt for a vanilla priest. The allegiance to Helm was more or less a by-product of LN alignment which feels best suited for the "inquisitior-ish" character.