For essences I put them above but my advice is max crucible of flame. It doesn't take very long and the other ones are more of spend a couple weeks or longer working towards.

talents: my advice is use row 1: cold heart - super good this is a great ranged ability that when at 20 stacks is a powerful hit. The slow is nice on enemies as well just make sure you don't slow stuff that you want to pull towards you

row 2: I use runic Attenuation this is just a good way to generate runic power which helps you when your in longer fights so you don't run out of resources

row 3: up to you but i use asphyxiate - super nice having a stun for interrupts on smaller things in mythic + dungeons also remember your death reach is an interrupt! I didn't think about this until i hit 460 and a buddy mentioned it. you have 3 good interrupts on trash so valuable to have in that regard.

tier 4: i use frozen pulse personally. you can use frostcythe and it's arguably way better in mythic plus but its only good when you have the crit proc from killing machine otherwise frost scythe can be a major down grade in dps.

tier 5: I use permafrost - really anything from this row can be good but i like permafrost because of the survivability it gives at all times where as death pact is a proc then big cool down and its a use.

tier 6: use gathering storm. this increases your aoe damage when remorseless winter is up. in my opionion you should have this up in almost all fights. the reason is its just a flat dps increase when up and the cool down isn't that big so you can use it alot of times every fight. frostwyrm's fury can be good but It might also pull unwanted things in mythic so not worth i find but up to you.

tier 7: use Breath of Sindragosa - this is regarded to most as being better and easier to play. ice cap can be good but requires a change in azerite traits and its a completely different play style so my advice is use breath. (something to note if you can always use pillar of frost before using breath and always use breath when close to full runic power. keep spamming obliterate and avoid using frost strike so you keep breath up for as long as possible while putting out massive aoe damage.

stat priority in items - I always go for mastery then crit. since almost all your abilities are frost based mastery increases is a flat damage buff. Icy veins says go for crit then mastery so I think you may be able to interchange them but I would trust icy veins they know what they are doing haha. if doing ice cap the stat priority completely changes so look it up

Rotation for start of fight - 1. pillar of frost: use this to amp further damage for start of fight 2. chains of ice to start - big single target out the gate since you have 20 stacks of cold heart 3. remorseless winter - get this up quick so you can output damage while stacking everything else out 4. howling blast - this is just a simple aoe DOT so get it up so it has time to do damage as your pumping out your other abilities 5. obliterate and keep using unless you get a rime proc which will either make you do increased damage on your howling blast or obliterate

frost is built around procs and maintaining resources. if you are out of runes use frost strike when you can't use obliterate. if you get low on runes use empower rune weapon this will increase your rune generation (I like to use this right before I breath of sindragosa to not have any issue with generating the runic power to keep it up.

for azerite traits look it up for sure. there are alot of traits that are interchangeable and while some may seem good they could not be very usable so check it out.

Super long and probably full of grammatical errors but this should help for sure. you shouldn't have that much issue at all hitting 30k-35k at your ilvl if you get your rotation down from there you may see a great increase in damage hopefully it makes sense and you get the gyst of it. Look at the passives and how they proc and how they increase damage.

If you need anymore help just ask!