transit visa for indian passport holder in Daegu or Busan (South Korea) on the way to Khabarovsky or Vladivostok (Russia)

I have an Indian passport, Japanese residence card and intend to visit Khabarovsk and Vladivostok (Russia) but an itinerary (the cheapeast one) involves a transit in Daegu (TAE) or Busan (PUS). I have a valid US Visa (B1/B2) but that won't help in any way i guess.

I couldn't tell from Timatic whether I need to apply for a transit visa in advance or whether a visa-free transit (or on arrival) is feasible. I have checked the other post (Can transit in Japan or korea) but it is closed without a solution. I know that Indian passport holders can visit Jeju (CJU) but not Seoul (ICN), and can transit in Seoul(ICN) if certain conditions are met, but unclear about Daegu (TAE) or Busan (PUS).

In this case, i will possess a valid e-visa for Russia, as Timatic says:

Nationals of India who travel to Blagoveshchensk (BQS), Khabarovsk (KHV), Petropavlovsk (PKC), Vladivostok (VVO) or Yuzhno-Sakhalinsk (UUS), can obtain an e-visa before departure at https://electronic-visa.kdmid.ru/index_en.html

(application form at https://evisa.kdmid.ru/)

Qn 1. Please clarify the rules applicable for a transit in Daegu, and guide how to apply if visa applications are required prior to the trip.

The itinerary for KHV via TAE is as follows:

Flight TW212, NRT->TAE

Flight TW437, TAE->KHV

Flight TW438, KHV->TAE

Flight TW211, TAE->NRT

The itinerary for VVO via PUS is as follows:

Flight KE714, NRT->PUS

Flight KE5989, PUS->VVO

Flight KE5990, VVO->PUS

Flight KE715, PUS->NRT

Qn 2. If i were to transit in ICN instead of TAE/PUS (flight sequence TYO-ICN-KHV/VVO-ICN-TYO), i don't require any transit visa applications, is that correct?