ok,tough questions

[Ivan141]

1st...post some pics of your engine and waterpump, if you have the rear waterpump housing of an original ae86 4age (which is not unlikely) then you can simply put a thermostat in there, otherwise just find an inline thermostat housing that fits your enginebay and place it in the watertube leading from radiator to waterpump. Be carefull though, the stock cooling system has a bypass for coolant flow around the thermostat, I think you'll need to have such a bypass in place if you want to use a thermostat.

AE92 and AE82 use remote thermostat housings, they are clunky but have connections for water in/out and bypass.

2nd
To use an oil cooler you need to have the sandwich plate that sits under the oilfilter, it has a nozzle on the underside, where the oil feed to the cooler comes from. I think you could probably take this from any 4age that has one. After that all you need to do is weld a nozzle for the oil return line somewhere high in the oilpan.