Bought an old house: recommendations for softner and boiler install

Do you have hard water? If you're not sure, go get it tested. You can even go to a pool/spa store and ask them to test it. Tell them you're shopping for a hot tub and just want to know what your water hardness is coming out of the tap. If your water is hard, get a softener. If it's not, don't get one.

As for a hot water heater, figure out what you want first. Do you want gas or electric? Gas is more upfront but cheaper every month. If your furnace or existing water heater is gas, then I would go with gas. The line is already there. If not, then I would go with electric. I wouldn't bother running a new gas line just for the water heater, unless your furnace is getting old and you're thinking of switching from electric to gas (I would).

Also decide if you want tankless or not. If you're not sure, just google tankless vs tank and read what it says. The various pages will all pretty much say the same thing.