Converting My Campaign To D&D 5E: What Happens To Previous House Rules?

Addressing old house rules is an area where my conversion priorities could have come into conflict.  To recap they are:

1. Keep the game fun, do not overwhelm with rules or required details.
2. World over rules. There will be no retcon to force the world to conform to the rules.
3. History over rules. See above. If necessary, there will be a minimally invasive explanation regarding anything in the rules which makes history inconsistent.
4. Minimize house rules vs 5E RAW.
5. The guiding principles are in order of priority.

My intent would be to make as many of the house rules go away as possible, and start our 5E experience as RAW as possible.  Fortunately, I am finding the conversion to 5E is making many of our house rules obsolete because the spirit of the rule, if not the rule itself, is in 5E.  

Below is a listing of house rules with comments on how I am going to address the rule in conversion.  Green indicates a 5E covers it well and there is no need.  Yellow indicates I am not certain but will go with 5E RAW.  Red means we still need a house rule to play the way we want to play.

• Arcane Spell Failure for Armor: If you were proficient in armor, you could cast in armor.  Now standard in 5E.
• Area of Effect Attack: Player attacker rolls dice instead of defending monsters.  This is a variation of players roll all the dice.  We may reconsider this again in the future, but its nice it is discussed in the DM guide.
• Building NPCs Building Characters, Monsters & NPCs: Build these as the DM needs for encounters, not holding to the standard character generating rules.
• Cleric Energy Blast turning replacement: Instead of the swingy turn table, and undead who stood around and took range damage until they were destroyed, clerics did damage to undead in the blast.  I am not sure we will stay with the new 5E way on this but adding they stay back until attacked at least solves part of the problem.  I am too new to the game to know if the turn results are as swingy as before.
• Creating Magic Items: Was a revised formula for creating magic items cost vs. time options which did NOT include XP costs.  I am fine to try the RAW in 5E because there are no XP costs.
• Critical Hits: Removed the broad exemption on undead and constructs being immune to critical hits.  Some creatures, like oozes, would be immune, but it was fewer, and if you could make a case for a critical, your 20 would give you one.
• Death Dying and Negative HPs: Instead of dying at -10, you died if your negative was 1/3 your total original hit points, reducing the chance for higher level characters to die on one hit when they were in single digit hit points.  Also had death saving throws each turn when below 0 hit points with three failures meaning death, and a 20 meaning you stabilize.  Healing brought you to 0 hit points and then added healing to that number.  I like the 5E system as is so far.
• Defensive Disengage: Codified what was already in the rules, but made the language more clear for our game.  Like that 5E has disengage action.
• Effective Caster Level: Multi class characters could add levels in other classes to their overall caster level.  Other caster classes as a full level, none caster classes as a half level.
• Flanking Rules: Made flanking easier to calculate and expanded what counted as flanking slightly.  We will play without flanking for now and see how it balances out.  We may find we do not miss it.
• Massive Damage: We put this in place to make falling more dangerous, and to offset the fact we instituted a higher starting hit point rule.  We will play RAW for now and see if we want to use the optional massive damage rule as time goes on.
• Paladin Smite Enemy: Ruled that Paladins could smite more than just 'evil' creatures.  Allowed that Paladins were wise enough to use their smite power against enemies appropriately.  5E seems to have this covered nicely.  
• Shrug Off Damage: Fighters could take a standard action once per encounter and get a hit point benefit very close to Second Wind.
• Sorcerer Character Changes: Changed Sorcerer hit dice from d4 to d6, and gave them some other unique abilities to further differentiate them from wizards, including a metamagic feat at first level.
• Spell Acquisition Arcane & Divine: I'll skip the long complicated rule text and just say we used spell slots.
• Spell Limits Zero Level: Casters could cast unlimited cantrips.
• Starting HPs: Added constitution total to starting hit points.  With the change to bounded accuracy, I am much happier with how starting and later hit points balance against challenge.
• Unified DC for Spellcasters: All spells for all levels used the same DC based on character ability score and level.  I am fine with how the proficiency bonus works with this instead of using pure level.

Notice there is no Red?  I had not reviewed each house rule in this context prior to writing up the list and assume I would have at least one thing red.  What surprised me most is how many of our house rules are now just rules, either exactly or in spirit.  This is why we are finding 5E very comfortable for us.

The dice never lie.