The OSPF implementation is odd, and works a bit differently on MXes than it does on L3 switches if I recall correctly. I do know people who are using it though.
Meraki is not CIsco enough to support EIGRP. I don't see how K value tinkering fits into the general design thinking behind Meraki kit, honestly. Where's that going to go on the dashboard?
I wouldn't expect IS-IS either.
If you have basic questions, I usually go to the document base and pop the basic keyword into the search bar. That's all I did here, besides make jokes about EIGRP.