Farm and house water system

I've been looking and searching, gleaming nuggets of good info here and there. I'm looking for best practices, Do's, Dont's, wish I thought of that's, and other info on putting together a water system for the farm. I will be using professionals where warranted. But at the moment I need to put together a good plan to go for.

Just bought a 105acre farm south of Farmville, VA. Have. ~3.5 acre pond in the middle. Currently found that the house has a hodgepodge of patches and make it work solutions that all together don't work. Not enough water to the kitchen sink to wash dishes or fill a teakettle. Other sinks in the house are fine. Newer well. Old well next to the house is unknown on why they drilled new one.  5 different types of piping under the house. Pretty much best solution is to replace entire water system in the house. There are advantages to this.

My current thinking is to add a 200 gallon rectangle tank in the house, and a 2500 gallon tank by a central utilities building. Fill those with a float valve/switch. Then use separate pumps off of those tanks for the house and irrigation/farm. Also thinking of doing a similar 2500 gal tank by the pond. There is also a set of springs/creeks not too far from the house and down hill I was looking at making another pond and plumbing all the house cutters to.

I'm confused on pipe size in the house. I'm thinking the house would centralise some of the irrigation to the front and side yards surrounding it. Should I pull in a separate 1-1/4" to 2" pipe from the big tank just for irrigation? Or do I plumb in from the house tank as part of the fresh water system of the house? I have been torn on using 1-1/4" PEX or 1" PEX for the cold water line in the house, as it may be utilized for irrigation and to reduce friction?  Probably overkill but I'd rather only do this once.

Thanks

Well -> Well pump -> Pressure tank -> spin-down filter -> big blue filter -> manifold (Think circuit breaker for water, so that each room get the same water pressure/volume).

I would irrigate with the spring if possible or with the old "shallow" well.

We have well water, we have a pressure tank, we have an osmosis system at the kitchen sink to reverse all the calcium that eats up appliance...

You are in VA, so colder than my tarm, and i suggest using pex when possible.  
Frozen pipes break, but pex is tougher, as it can flex without breaking.  The extra cost pays for itself, in many cases