Metal Halides & T5 works just fine. Its a matter of preference basically. T5 covers a wider spectrum compared to MH, n since u are not into sps, T5 can be a replacement for MH.
Denitrator is a plus point, not a must. Since u said u have a budget, its best not to get one as its not cheap to maintain one. The demi balls are $2 each.
Calcium reactor is good. . but again. . . its just a bonus but ur corals can do without it. Dosing is sufficent.
There are two schools of thought regarding DSB. i dun think i am fit to discuss it here.
u can replace the Uv sterliser with Ozonizer.