To answer yr qns in a simpler way:
Ans 1: get a overflow box from out sponsor,eaquanature, if yr friend does not wish to get a new tank
Ans 2: The efficiently of the Bios balls will be determined how it's used(wet-dry filteration), CORRECT ME IF I'M WRONG. If not , over a period of time, NO3 will build up and this is wat we called nitrate factory.
Ans 3: Lighting use should be depend on wat u want to keep.
eg: softies like mushroom = PL, T5
Hard corals = MH
Ans 4: For his tank's size, go for 1/2hp or higher
Ans 5: Scape the UGF, that was used 10 to 20 years. Go for at least DSB(deep sand bed)
Ans 6: I hope I got is right, u're refering to the type of sand use...Then go for affordable coral 0 grade sand
Hope this helps