I've found them to fire in this order. Nothing in the docs to my knowledge, but just tested to confirm:
The problem being is that you are importing Bootstrap 2.x which comes shipped with Joomla (coming via <jdoc:include type="head" />) and Bootstrap 3.3.5 via the following link:
which I assume you've manually added or is coming from the component.
You've also got the following jQuery ...
I use Ohanah on JoomlaLondon, certain it wouldn't be up to this. I think I can also help you rule out others I've used, although with overrides one or two of these could possibly be made to suit:
MiwiEvents, nice because it integrates with MiwiShop(OpenCart highly expandable).
RSEvents (Needs RSForms for reg and has limited payment gateways). No Agenda ...
I am using Event Booking on my personal site. It allows me to setup individual events and to collect registration details/payments for each event I create. You can see a demo on the providers site.
I am also using DPCal Pro on another website which just displays events around the globe. It too is supposed to be able to handle registration, but I don't use ...