Running First Session Soon!

Hey all, I've been a lurker here for a while now, and am running my first 5e D&D session as a DM for some new players. I thought I might turn to you all for refinement on my plans/schemes for them.

Out of the 5 players, 2 have never played before, 1 has played D&D for 20 years or so, 1 has played D&D for ~1 year, and the last has played other RPGs (Dresden Files (Fate system), Werewolf).

I've already created 5 basic level 1 characters out of the tropes for D&D. A Bard, a Cleric, a Fighter, a Rogue, and a Wizard; all human, all using the suggested stat list from the Player's Handbook. I'm using the suggested spells for ease of character creation as well.

My plan is to have all the PCs be from the same, small village. This gets over the "How do you know each other" phase. They may not like each other, but they'll know each other.

Setting: Farming Village surrounded by Thick Forest, High Hills with mountains nearby. Inn, Blacksmith, things like that are present.

Plot: Various animals are going missing, leading to a goblin cave, where they are nurturing a nest of the caterpillar dragons from this post: https://www.reddit.com/r/DnD/comments/6vbt2r/art_odd_dragons_smaugust_thus_far/

I'm hoping you all can coach me on difficulty levels (I've been reading the DM's guide) for encounters, and help make stats for the Caterdragons (in case they fight them/steal one). All in all, I'm hoping for a sounding board to refine quest hooks and the like.

Thanks in advance!

TL;DR: New D&D DM looking for advice, tips, and the like to make friend's first session fun.