hi bro,firstly..welcome to SRC
A 4x24W T5HO will be sufficent to keep both soft corals and LPS.T5s are a better choice than PL lightings as they dont not give out as much heat as the PL lights do.
its alright to use canister filters and they work good too for the skimmer,would recommend u the red sea prizm skimmer which is a hang-on and is less than $100 if u get it second hand from the pasar malam section.U can also use thoose air-stone skimmers which are about $10 n requires a air pump,but regular water changes are recommended.As for the powerhead/wavemaker,if u r lucky u get get seio620 or 820 second hand at the pasar malam section for about $30,if not maxijet powerhead are a gd choice too
u can try coralife salt as its not expensive and will do great for ur tank as u r only keeping soft corals n LPS.Yes,its good to also use distilled or DI/RO water for water changes or top-up as our tap water contains silicates n phosphates which causes aglea bloom and can harm corals n fishes too.
Hope this helps,cheers