Having a good User Interface is key to perfoming at a top level. Everyone should build their UI around their own needs. Think about what you want to see and don't just copy someone elses Interface.
However here are some Addon recommendations that everyone should get:
Weak Auras 2: Great Addon to track every kind of buff & debuff in the game that basically every top raider uses.
BigWigs/LittleWigs: BigWigs is a great BossMod that is easy to setup and very customizable. It usually is the most up2date BossMod. LittleWigs does basically the same for dungeons.
Classtimer: Classtimer is a great Addon to track your DoT's. It is very easy to setup and fullfills all the needs. There are some other good options like Gnosis or even Weak Auras out there too.
KuiNameplates: Good nameplates are really important for every class and even more for DoT-classes. KuiNameplates is one of the more popular Nameplate Addon choices. However there are some other good ones like Plater Nameplates or TidyPlates.
If you are more the lazy type and don't want to build your own User Interface I can highly recommend ElvUI. It has a lot of options and is also aesthetically very pleasing.
I personally don't use many macros for PvE as I don't really see the need. However I listed some that might be useful for you.
/cast [@target] Shadowfury
/cast Spell Lock
This macro is important because the Command Demon ability is often bugging out.
/cast [target=focus] Spell Lock
This macro will interrupt your focus target. It requires a focus target beforehand.
There is a lot of great Weak Auras out that can be found on Wago. I went ahead and searched for some good packages that people can use if they're not good at creating own Weak Auras.
I can also highly recommend getting the Soulstone Reminder from Nnogga. It will always tell you to put your Soulstone on a healer. Only works in a Guild Raid though.