BQ25750: Design help - Parts Selection

Tool/software:

I need some help selecting the ICs/parts for the power distribution board /Battery charger that I’m designing.

The board consist of 1x Input, 4x output, 1x Battery connector, 1x external charger connector and 1x USB type C PD. The board is supposed to take power from automobile via cigarette lighter port to charge the LiFePO4 (4s cell) battery and supply power to the 4x downstream ports (external load, capacitive or resistive), it will also have an option to charge the battery by connecting an external charger. In addition to 4x output, it will have a USB type C connector supporting PD 20V,5A (source) to charge devices like laptops (only power, no data).

In normal case the vehicle will supply the power but in absence of input or in case of voltage drop / insufficient current it will switch to battery to provide power to external loads.

Priority is supplying power to the load and remaining will charge the battery.

It needs to support following:

• Supply Input
  Input to the board will be coming from car cigarette lighter port or the car battery 12V/24V
  voltage range: 9V – 30V DC,
  20A continuous max input current
  
  Protection required on input side:
  OV, UV, inrush, short circuit/overcurrent, reverse polarity, reverse current
  
  parts shortlisted:
  eFuse: TPS1685 (but has no reverse polarity protection) + LM74700D-Q1 (for reverse polarity)
  Ideal diode: LM74910H-Q1 or LM74910-Q1 or LM74930-Q1 (one of these)
  
• Battery Input
  Voltage range: 9V – 48V DC
  15 - 20A charging/discharging current
  
  Protection requirements / additional feature:
  OV, UV, inrush, short circuit/ overcurrent, reverse polarity protection
  
  Need to monitor the charging and discharging current and be able to cut of battery path when desired.
  
  Bi-directional Power SW with reverse polarity protection?
  
  parts shortlisted:
  Reverse polarity controller: LM74502H (will this work?) From datasheet it seems that Vs pin needs power, how do you suggest doing it incase we want to power it in either case battery or input?
  
• Outputs (external loads will be connected here - capacitive or resistive loads)
  total 4x ports
  2x to support upto 10A and 2x upto 4A continuous current
  Be able to turn it on/off (enable/disable) and monitor current.
  
  Protection requirements / additional feature:
  Inrush, short circuit/ overcurrent
  
  eFuse: TPS1685 (Can this be used?)
  Or
  High side SW controller TPS4810-Q1 / TPS27SA08-Q1
  
• External charger
  
  voltage range: 9V – 30V DC,
  10A continuous current
  
  Protection requirements:
  Short circuit/overcurrent, reverse polarity, reverse current
  
  parts shortlisted:
  eFuse: TPS1685 (but has no reverse polarity protection) + LM74700D-Q1 (for reverse polarity)
  Ideal diode: LM74910H-Q1 or LM74910-Q1 or LM74930-Q1 (one of these)
  
• USBT type C
  Supporting power delivery upto 20V/5A (100W)
  Only power source to end devices, no data.
  
  Suitable Buck-boost converter (PPS) and PD controller for this?
  

For the above could you suggest the right parts for the listed protection, I shortlisted few, but a bit confuse as which one to use, please point out if there is a better alternative suitable for the application. It seems like some parts like the ideal diode controller and eFuse have more or less same features

For the Battery charger IC, I was looking at BQ25756 and BQ25750 but not sure which would be right for my application. (just need current to flow in one direction from input to output, reverse current flow is not required)

• Do any of these support battery supplement, suppose if input current is not sufficient to drive load, then excess current can be taken from battery at that time (load sharing between battery and input)? 
• How will BQ25750 react in case input current is not sufficient to drive load, will it keep switching between input source path and battery?
• Why are MOSFET's marked as optional in BQ25750? without MOSFET how will it manage the power path? 
• Regarding the BQ25756 , from datasheet the system/load and the battery are on the same node does it mean the charging current will be shared between load and the battery.
  What if load needs to be prioritize , can it be done somehow ? or what if there is no load at all would all current then go to battery since battery has max charge current limit as well. 
• How does BQ25750 react to short circuit, since it has current sense and limit feature , is it good enough or is it required to add efuse before it?
• Is there a way in hardware for BQ25750 to forcefully turn off the battery path (turn off discharging)? I think the input path can be turned off by pulling the ACUV pin low.
• Since I only need current to flow from VAC to SYS or BAT, can I remove one of the MOSFET out of Q1 or Q2 , maybe Q2 and the reverse current through body diode of Q1 will be blocked by input protection ?

thank you