1) By duplicates, what do you mean by that? You can use the same video in a couple ad variations just make sure that you are testing something. Wether that is different ad copy or different targeting. That way you can stack up what can improve your ad. I do recommend adding a few different ad types to the mix as different formats can cater better to the creative you have and resonate with users differently.
2) How many times should you dupe out the video? You can dupe our the video as many times as you want but what you need to be careful of is post fatigue. If you have a super high frequency (12+ imo) then you’ll want to consider either more ads in the mix, loosen your targeting, or look at you budgeting. Example – if you have a small site and are running a remarketing campaign even $10 a day could be budget overkill. You don’t want to pepper people with ads, especially if it’s the same exact video.
3) Before I start my campaign I usually set my stops. IE, “if I don’t get a conversion after spending $200 I turn it off” choose what is comfortable for you / your client.
4) Make sure your Facebook pixel is set up properly and your UTMs are golden!
Make sure you have a remarking campaign of some sort even if it is small. Those people have already visited your website and are further down the funnel.
Hope that helps