ADU - Garage Conversion

[Naven Meas]

Hi BP community! First of all, I'd like to say thank you to everyone out there for providing great content and feedback on these forums and blogs. I've definitely learned a ton just by reading and listening to the BP podcasts and I figured its time to finally Jump in and get started! 
So I came across this great opportunity in the City of Long Beach, which has a detached garage that im looking to convert to an ADU. I checked the city ADU guidelines, and the property does meet all the requirements. My question is, what exactly should i expect in terms of the construction costs, timeline and permitting process? I know this may be a lot to answer but any ball-park answers will by much appreciated.

Thanks!