More repat Qs related to Visa / Green card for my UK spouse

I've been reading through some of the recent questions and responses, which are all helpful to me, so thank you!

My situation: I'm a US Citizen living in the UK with my UK spouse (and 2 kids) for nearly 2 years. I would really like to return home. He is currently interviewing for a position in the US, but I don't anticipate the company sponsoring him for the move. They know he's married to an American and I believe the conversations so far have been under the understanding that he will apply for entry based on spousal status. ANYWAY, I'm just trying to get our ducks in a row so that IF he gets the job we can move as quickly as possible.

I just have a few follow up questions -

1) I'm confused about the processing times. Seems like different answers on different posts. What's the average time is takes to get the visa?

2) I'm assuming it is faster to apply DCF rather than mailing the documents to Chicago, is that correct?

3) One contributor mentioned that her family moved to the USA after making the application but before her husband was approved. Is that allowed? Not being cheeky, just wondering how that works.

4) Anyway to fast track this? I read about a K-3, but it says you have to apply in the country you were married. We had a destination wedding in Mexico, so I'm not sure that's a plausible option. Not that I'm against an excuse to go back to Cancun.

5) My husband previously lived in the USA for 10 years. He was on an E-1 Visa and then a green card holder. He returned the green card when we moved to the UK. Will this help us? hurt us? be of no consequence?

Thanks in advance for any help with any or all of these questions.

1. The average time the embassy tells you to expect is 8-10 months. Right now they're processing I-130s in 6 weeks, but that can change in a heartbeat.

2. Yes, as the USCIS field office here is taking six weeks, rather than several months, to process I130 petitions.

3. Yes, it's allowed. You could have just asked. You can travel while its processing. He entered the U.S. on the VWP as normal. He couldn't work, and should the processing time have gone past the time allowed on that, he would have left until it was finished.

4. Direct Consular Filing IS the fast track option. We have the fastest processing time out of anyone.

5. As long as it was surrendered appropriately and he never overstayed anything, then it won't be of any consequences. My husband had a prior K-1 visa when we did DCF, didn't slow things down at all.

Thanks so much for your reply, Gwen. I didn't name you because I didn't want to "call you out" or make you feel obligated to reply.  Thanks again for all the information, exactly what I needed to know.