Build it as a 3 level class, as that's the standard way of doing things around here.
The blindsense thing feels forced.How about something like blindsense out 5'+5' per point of Wis. mod? Or maybe the saving throw for poison is based off of Wis? That way the Blindsense, Poison, and Vermin Empathy are all based off of Wis. Plus it can multiclass into monk, which uses Dex and Wis as it's main scores.
Also, I just figured out that the poison the 3.0 Ettercap has is different from the poison that the 3.5 Ettercap. Now I'm thinking that a bonus damage progression would be better than a die size progression.
The poison goes against common sense.
Overall, there's really no need for the wisdom bonus or stuff being based off of wisdom.