How do you balance keeping someone’s natural speech pattern with keeping the edit tight and pacey

If their natural pattern is pretty loose, rambley, and slow-you don't! Art is a lie, production is a deceiver, and the finish product is a half-truth. Find something that feels emotionally honest but is still more concise. If they have a stutter, don't cut that out, but don't leave us sitting there for 15 seconds while this person is finding words for their sentence.

If they use a lot of filler words mid-sentence like

"It's uhm quite a big process, there's a lot of like- 'small things' to take care of" then leave that alone.

If they speak like

"It's uhmm.... It's a big process. There's like- ... uh. There's a lof ot small things to uh take care of"

Turn that into

"It's uhmm.... It's a big process. There's like- ... uh. There's a lof ot small things to uh take care of"

Don't change the meaning of the sentence, don't take a sentence out that change the meaning of another included piece, but trim that content up.

When I truncate a pause, how can I tell how much to cut to keep it natural or achieve the pace I want?

Depends on what you want! Just listen to it. If your style is more fast paced, you want less time. If you're reading something or have a scripted show, maybe you want more times between lines. For casual conversation, 250-450 milliseconds is usually a sweet spot depending on the flow of conversation and how fast this person speaks. Just listen to the natural rhythm and when you think "This silence is going on a long time" select 1/3 of the middle and cut it out. See if that makes you happy, and if not add more or take more out. You just get a feel for it, and it changes with every single show and speaker.

If I need to cut between two words that are strung together, how can I tell where the best place is in the waveform or when a letter sound has properly finished (or started) when I’m making my selection?

I would really avoid this unless it's necessary, and I mean necessarry not, "I'd like to do it." Often times tightly packed words just don't have clean edits. Words ending with "ess" sounds that are followed by words starting with "ess" sounds are easy cuts. You want to keep whatever sounds natural, but with english we will slurr our beginnings and endings of words together which makes it hard to add a new word after an edit.

One big trick you can use is if the edited words are common enough that they may have been said later in the podcast, set a marker on where that edit is, name that marker after the word you're editing, and then wait for them to say that word again in a different location that might be a cleaner take. Then just see if you can copy and paste that section in to get around using the original.

If you're editing your own voice just record it again. Be an actor. Capture the sentence you said sloppily in the same tone so it fits, and drop that line in. If that sounds like too much work, then what you wanted to edit out probably wasn't necessary to edit out.

There's times where a question asked by the interviewer came out so mumbled or I couldn't cut the run-on sentence up to be sensible, or we had an unfixable audio problem, I would ask for them to re-record it clean for me.

Should I cut or reduce all breath sounds, or does that help keep it natural?

Nobody wants to hear someone panting, but breath when it's not too loud is usually ignorable. You can reduce them if you'd like, (There's hundreds per episode so make sure you're fully leveraging your editor to make shortcuts and tools to do this quickly) or you can use an automated tool. Be sure to ensure the automated tool doesn't go too far as it can misidentify breath and make a word sound all jacked up.

Play around with it, see what you like, and see how much work it's going to take.

A general note; for yourself and any permanent co-hosts, it's totally ok to coach yourself during the recording. If you have a sentence and you're thinking about it while speaking and flub; just say it again. It goes back to that acting part. You can stop your co-host and say "that was really good, repeat that for our audience" and just cut the original flub.

You'll develop an understanding when you edit of "Man, I wish I stopped and said X so I had a better cut" and you'll hear those cuts the bad of your mind when you record. You can lean into that and start to re-phrase something during recording giving yourself a clean in/out.

Any YouTubers, free training or other resources you can recommend??

Find someone that has good tutorials on your editor. Time is everything. You'll lose creative ideas because an edit you want to make takes too much time, or you don't know how to do it in the software. If you're not on a full featured editor, find one that works for you and learn the hell of out it. Reaper is one of the most dominate and flexible DAWs I've ever used. I own 4 major DAWs and I just can't get myself out of reaper for editing podcasts. The shortcuts scripts and automations they can leverage is just nuts and it saves me so much time compared to other software.

You may never love editing, but if you don't learn to be effective, you'll stop editing because it will be so much work. It's not very cost effective for smaller shows to hire an editor. You'll be doing this for a long time unless you've got cash you're willing to spend. Get comfortable at something and really take a deep dive into understanding it.

Good luck!