Obviously, the live read ads by the podcast hosts will still be there, but yep, the other ads are all usually targeted ones inserted when you download it. Once it's downloaded, you can change your VPN back to wherever so you don't have to deal with every site defaulting to Thai or Japanese lol.
This works better than the "skip x seconds" idea others have since some podcasts have mid-show ads, too.
If it's one of the podcasts that uses a service to auto-insert ads, you can always change your VPN to a country that wouldn't be relevant and it'll usually download without ads. It almost always works if I set mine to Japan or Thailand.
What's the best way to compress mp3 files but still retain the quality (even possible)?
If you're not starting from a lossless format (like FLAC), you shouldn't really be compressing anything. When compressing from a lossless format to MP3, it's totally subjective. When I was more into ripping CDs, I'd do V0 or 320 - there's probably plenty of internet arguments by people more knowledgeable than me if you need a breakdown in different MP3 compressions.
It comes out with a dull ass steak knife stabbed through the top
I've used Kotatsu. It's pretty good for all kinds of comics (not just Japanese manga).
You can download chapters while on WiFi and read without using data.
Is that an I/O shield for a motherboard?
Xirup's phone is hentai free. Lookin for it? Leave. 
Jokes aside, mangakakalot, mangalife, and manganato seem to work well and have a wide selection. If they're not working for you, maybe try a fresh install?
If you're delving into bootlegs, you might just need to be prepared to run into NSFW content, though.
Haru asking Futaba where she has to type in her dad's credit card number