I'm a full STR 192 DRK, Stats included and I'm looking to tank A1S for the first time. I can do a1-4 norm. I'm looking for some advice on a few things:

Can't afford pentamelded so how many slaying vs fending accessories should I run? Do I need to reinvest all my stats into vit?
What's a good amount of total HP to hit before I can invest into Str again?

Any tips on when the best times to drop tank stance for a bit to dps would be?
Does the oppressor use royal fount at all the same times as on a1 normal?

And just any random tidbits of advice you can give me that will make this easier on myself and my team. I'm confident in my damage output (in full STR atleast, never had to try anything else so far ) and I'm confident in my cool down rotations except timing Dark Mind since not many bosses have magical tank busters but I atleast know when to pop it in a1 normal