Dan h is correct but if it’s electronic ignition the power consumption required is minimal [ very little is needed]therefore it would be OK to put on boiler circuit……………………..as for the bedrooms i personally put on separate circuits ……… to save money i would run 12/3 w/grd then you would have 2 circuits in one wire …..you can share one nuetral for 2 circuits its allowed by the CODE……… as for the plugs ….you can use as many as you want ……. i wouldn’t put more than 6 recepticals per circuit including bed lights is OK

Your boiler pump is usually on it’s own circuit.

Your gas water heater doesn’t usually require power, unless you have a circulating pump. that pump can usually go on another outlet circuit.

Check with your local building codes as they vary from jurisdiction to jurisdiction.