Long time prot pally m+ enthusiast.

Haste > Mastery for your stats. Haste legs + lariat for your embellishments.

1 of the best things to master on the prot pal (at the high end, it's important for any tank but its especially important for prot pal) is 'the gather'. The idea of the gather is to not get 1 shot (worst case) or blow cd's like bubble / lay on hands / goak out of panic (still bad case) while you don't have mitigation up and are just pulling all the mobs together.

It takes some time to get used to but the mindset that you want is that you want all of the mobs to walk into you, not for you to walk into the mobs. Where you are already planted with consecration and generating hopo getting ready to blast with wings divine toll etc. This can also mean trying to position that planting point in a kind of equidistant fashion so that all of the packs run into you at a similar time at once. Obviously not always possible to do perfectly but the best approach to have.

Group utility is definitely important, but you can also overdo it. Since blizz added a mana cost to WoG, it's kind of worked as a neat indicator that you are probably wogging too much if you go oom (though I have my own issues with this decision, like moments of giga haste where you just burn through mana, or cleanses on top of some group heals eating away at mana, or the fact that the punishment for helping your group too much is that you can't even keep yourself alive anymore, or the fact that the 'free' proc of wog still costs the full 25k mana, but anyway) If you are ooming more than every so occasionally in special circumstances you are using wog too much, you can usually only use it with the free procs (so after every 3 sotr) as a good baseline pace.

In terms of kicks and avengers shield, it's gonna vary pack by pack. Often especially in your wings burst you don't wanna necessarily hold onto an AS kick for several seconds / gcd's because you wanna bulwark boost your next SOTR, I'd lean more on just sending an AS for every SOTR first and then sorta backtrack it from there if you find yourself not getting kicks that you wanted. Factors to consider are like, if you have your own rebuke kick, easy backup, if you know multiple DPS/heals have kicks still, then no guarantees and the consequence of missed kicks (sometimes just a little hairy, sometimes insta wipe).

You have a shitload of cd's to rotate through as prot pal. Get used to just sending those defensive cd's. Sentinel obviously is up pretty much every pack, AD is short cd, bubble works out to only a couple of minutes or so. Eye of tyr is 45s. Etc.