Also note that you can get a better deal ordering from Eluktronics directly - $1999 with 1TB SSD and you get the gaming bundle, compared to your Amazon link that has 512GB SSD and no bundle for $2099.
But the caveat is that if you do order from Eluktronics directly you'll need to wait almost a month for it to ship. And if you want the bundle you can't customize as much - including liquid metal not being available. But you can always repaste it yourself, the paste is cheap.
I placed an order using my link above 3 weeks ago, getting anxious waiting for it.
I highly recommend delidding, I delidded my 3570k (upgraded from a Phenom II x3!!)
Applied Conductonaut between die and IHS, and MX-5 between IHS and Cooler and the temp reduction was incredible. If you want to delid, you should just go all the way and use liquid metal between IHS and die, it's not difficult. 1 gram syringe is MORE than enough, I was able to do 3 processors with only 1g, with perfect coverage.
https://www.amazon.com/Thermal-Grizzly-Conductonaut-Grease-Paste/dp/B01A9KIGSI
I also DO NOT RECOMMEND using a vice. Get a delid tool if you're going to do it. Rockit 88 (my preference) or Der8uer Die Mate 2 can do intel 3rd all the way through 11th gen, making it a tool that can be used in the future for any other Intel core platform you use. Worst case, you can resell the tool afterwards!
https://rockitcool.myshopify.com/products/rockit-88
Also i was wondering what is that material for isolating the cpu things that is near the chip? Can i get that somewhere and is it necessery at all?
3570k doesn't need anything isolated, there are no SMDs on the CPU! You got lucky with one of the easiest to delid chips
Also do i need to clean off the old glue and put new one or i can just leave it like that closed in the socket?
Yes you MUST clean off the old glue, just use your fingernail or something plastic that can't damage anything, make sure you get 100% of it off. You don't have to re-adhere it, the hold down bracket will hold the IHS firmly as long as it's in the socket, but you do need to be careful while putting it in the socket and make sure the IHS isn't sliding out of place, you'll get a terrible mount with your cooler.
For that reason, I would recommend re-adhering the IHS to the CPU. You can use 1/20 the amount of adhesive that intel uses stock, a tiny dot in each corner, and future delids will be very very easy if you really messed up your liquid metal application and need to retry.
Use this RTV Silicone, I squeeze a little amount into the bottom corner of a ziploc bag, then just cut off tiniest bit of the corner so you have a very very precise applicator, it helps immensely as the normal applicator for the silicone gets the stuff everywhere and it's a real mess, also it makes it easier to apply just a little dot of the stuff right in each corner where you need it.