joyh97

He is a scammer. Report the messages to fiverr and ignore him. 

Nope! As soon as the first delivery is completed, you have technically unlimited time to send a revision. The timer no longer matters. It still counts down, but nothing happens and it doesn't affect your stats once it elapses. The only potential downside to not delivering a revision quickly is that the buyer might get impatient and after days, weeks, and months of not delivering the revision, they might decide to cancel the order, or leave a bad review, but your stats won't be affected outside of that.

You should change your settings so that the order doesn't start unless the requirements are completed first.
You can cancel the order and explain it to customer service. I believe they have said in the past that if you cancel because you didn't have enough information to do the job, you can email them and explain and they will reverse any negative affect from the cancellation

I would contact customer service at support@fiverr.com
You could also try using a different internet browser or clearing your cache/cookies

Yes, it will affect your stats to deliver late, even if the client is ok with it.
If you are getting so many orders that you cannot fill them on time, you have some options:
1. Limit your orders. In the my gig section, you can set a maximum amount of orders in your order queue.
2. Increase your delivery time. The time you advertise should be the time you can GUARANTEE to finish an order in, without extensions. Adding extensions is poor customer service and unprofessional. 
3. Increase your prices. This should mean you will get less orders, but they will be higher value, giving you more time to deliver a better product overall to each client.
Extending should be as a last resort that is rarely done. Even if a client gives you a good public rating, this is something that will likely be reflected in your private feedback score.

I think my first gig video was approved within 48 hours. Now when I update it, probably less than 12 hours.
Not sure whether that's because the process is just quicker these days, or if it's because I'm a level 2 seller now, but I would expect it to be done within a day or two!
And yes, the gig video will automatically be the primary gig "image"

"In order to find my gig, I have to type the exact name of my gig in and it's about 10 pages deep."
This may be true for you, but not others. I've received a bunch of orders from new clients at a time where I couldn't find my gig either. The search results you find when you search your gig aren't indicative of everyone else's search results. The feature hasn't been removed, if it had, Fiverr would quickly lose business as no new sellers would be able to make any sales.
If people aren't seeing your gig, it might just not have been boosted yet because fiverr is still doing some manual reviews to make sure everything is up to scratch. Also make sure your gig title, images, SEO keywords etc have all been set up correctly, and you don't have anything that could be flagged in your gig descriptions etc. If you have something that could be (without context) taken offensively in any way, it could be causing issues with your gig being displayed.