Thanks for sharing this.
One argument I come across is that apart from being symbolic, individual action does not help #1,2 and 3. Elaboration / links to articles that try to quantify the "real" individual effect could probably make the case more persuasive.
If the "real" impact is small then one could argue that the slight inconvenience in following a vegan benifit is comparable to the small benifit that individual action results in.
The suggestions below aren't particularly EA-aligned but might interest you. Note that I am not a data scientist and haven't worked with any of them.
https://www.ideas42.org/ seem to work in your area of interest. I don't know if they would offer projects to work on though.
https://omdena.com/ has interesting data for good projects and can be a good place to build a data science portfolio (my partner volunteers for them and is quite satisfied with the experience).
https://www.drivendata.org/ has data for good challenges that might interest you.
Hop
The Good Technology Project is now also on FB and Twitter:
Apart from funding, are there other leverage points you see to move the animal welfare movement as a whole towards higher impact? As an example scenario: early hits causing other organisations to alter their strategy?