as for your heater i would mount it parallel to the sand bed about 4 inch from bottom in center of tank
1. hide behind rocks so you dont have to look at it
2. covers more surface area of tank for more stable water temp
i would place 1 power head on side glass towards the rear
and the other on opposite side glass towards the front
once there in you can adjust them to what works this will help give full circulation
if you go the 2 island method you can always get a flat rock to make a bridge for more surface area for coral
heres a pict of one of my old 40g tank to give you a idea about the bridge
as you prob can tell im a macro junkie its a good filler and cheaper till you have enough money for coral and looks good , start ups arent cheap
take your time and have fun
good luck with your build
if you need help feel free to ask
1. hide behind rocks so you dont have to look at it
2. covers more surface area of tank for more stable water temp
i would place 1 power head on side glass towards the rear
and the other on opposite side glass towards the front
once there in you can adjust them to what works this will help give full circulation
if you go the 2 island method you can always get a flat rock to make a bridge for more surface area for coral
heres a pict of one of my old 40g tank to give you a idea about the bridge
as you prob can tell im a macro junkie its a good filler and cheaper till you have enough money for coral and looks good , start ups arent cheap
take your time and have fun
good luck with your build
if you need help feel free to ask