Cheapest way to get some equipments will be go on graiglist and search.
compare prices at your LFS
u don't have to drill holes, u can always use an overflow box to direct water to the sump if u r planning to have one as well.
For saltwater, you will need a protein skimmer (some ppl use HOB
, but protein skimmer is better, at least thats what I have been told.)
you external filters can work as a powerhead, just don't put any media inside as it will only become a nitrate trap which u don't want.
About miracle mud, usually people use live sand.
miracle mud is used in refugium, don't know much about it, but have read one article said that mud messed up their tank.
get a RO
unit, it make your tap water sooo clean that your fishes will love you more XP, and for lighting, depend on what you r planning to have. (update your threadm, so others can help u as u go.)
I m just giving u some really basic stuff, more pro will add on later XP