Kitchen grey water for a cake maker...

I am in the process of purchasing a home. Long amd short of it is that it has a rather old septic system that has me concerned. I want to reduce the load to the system as much as possible to extend its life and also get some watering benefits onto to some future trees.  

My wife is a cake maker and is always working with and frostings and thanks to her business we are abke to make ends meet. We end up washing a LOT of dishes as a result and while we try to remove a lot of cream and frosting before washing but I know a lot of grease still makes it down the drain.  I honestly don't know what our average gpd since we are on a well currently.  

My general question is what is the best path forward in terms of grey water design?  

My first initial thoughts are:
1. Start with laundry to landscape to lower the septic load as this looks to be the easier of the two systems to operate.

2. With the kitchen system, is a grease trap in order or is the grey water sitting in the trap more of a danger than anything else? Would an initial small wood chip filter with worms or BSFL be the best initial option before going to either a reed bed or straight to a mulch pit?  

Hopefully I will be able to do a drawing of the existing conditions by sometime next week to get a better idea of the actual feasible options...

Finally, the codes for my area require a tank for grey water storage which as I understand it is a big no no.

Thanks for any and all suggestions as I have no experience with grey water.  

I have a laundry to landscape system on my back porch.
It drains through a mulch filter and waters the mulberry tree and grape vines.
It's half a IBC full of mulch and filthy water comes out clear on the other side.
If I ever make a kitchen system,  I'll send it through the same filter.

A grease trap cleaned regularly is always useful.
Make sure its easy to use, so that you do use it!!
I have baskets in mine I can lift and insert a clean one and then deal with the dirty one.

Water only stays in the grease trap until the next wash. They are not a concern.
Grey water systems as such should not hold water longer than 24 hours.

As for water usage, purchase a water meter they are not expensive but the are useful.

Separating the water flows always helps as well.
I think you are doing well with your ideas.