Multi-hop transit visa in Addis Ababa and Dublin clarification for Indian passport holder

I'm hoping to fly this long-haul multi-hop trip to reach San Diego on the west coast of the USA from Tokyo, Japan by flying westward. I have an Indian passport, Japanese residence card and valid US visa. I am ready to book it ONLY if there is no need to visit embassies to get a stamp/authorization, as a "transit visa" might be required.

But before I book it, I want to make sure that all I need to do is book the tickets, pay the price and take my passport and residence card along when traveling.

I used timatic via http://cms.olympicair.com/timatic/webdocsI/spdbmainv.html

Transit points are Hong Kong, Ethiopia and Ireland.

Please help me understand the tansit without visa (TWOV) rules at Addis Ababa (ADD).

Am I eligible to transit at ADD while flying from HKG to Dublin, Ireland, considering that both HKG and DUB are themselves transit points for my journey?

Why I am worried/why is it unclear to me?

Please note the layovers are 16 and 15 hours respectively. The arrival and departure dates differ (by 5 minutes, oh god) on the westward leg but not on the return eastward leg.

Timatic says:

Visa required, except for Passengers with a confirmed onward ticket for a flight to a third country within 12 hours. They must stay in the international transit area of the airport and have documents required for the next destination.

Visa Issuance: Visa required, except for Passengers can obtain a transit visa at Addis Ababa (ADD) if transit exceeds 12 hours and if they have confirmation that a visa has been approved before departure by Ethiopian Airlines. The maximum transit time is of 24 hours.

In my case, I have no documents (visa) for the next destination (DUB, Ireland). I guess I need to apply for some kind of Ethiopian transit visa before departure by Ethiopian airlines. Do they charge any fees for that?

The page at https://www.ethiopianairlines.com/AA/EN/information/essential/visa_and_immigration_requirements says:

Visas are required for all foreign visitors to Ethiopia

and

nationals of 36 countries are now allowed to receive their tourist visas on arrival in Ethiopia at the regular charge.

The list contains India. So, would I be charged? How much? Do Ihave to pay twice, one for each leg?

What is the guarantee that I will be granted one? What if my application is rejected, will the airline refund my flight cost?

I made an assumption there that I need to apply for a transit visa by asking Ethiopian airlines to arrange it for me, and that this can be only done after making a booking. So it's a deadlock, whether I should make the booking first or apply for transit visa separately (chicken or egg).