I use about 2.5 times as much alk as calciumAlkalinity and then calcium will be the first things you notice dropping. An easy solution for both is Kalk. Or you could dose them separate, sodium carbonate for Alk and calcium chloride for calcium . (I settled on Kalk as is was easier to dose 1 than 2 things and things stayed where they were needed.) Alk and calcium should be used up proportionally in a reef tank.
As far as the trace elements, if your not overly stocked, weekly water changes should keep them stable for now.
The KZ 1234 is an easy system to use. There are a lot of options out there. I think the cheapest being Seachem trace and Seachem Plus. But Seachem has some good products and some bad ones.
Also All for Reef is an option, not everyone likes it, I have had success with it but others haven't. It's an All in one, for Alk, Cal, Mag, trace elements. You do have to check and possibly bring the big 3 back in line occasionally. It helps maintain them but it's possible for them to get out of wack still. The powder is the cheapest long term option, I wouldn't buy the premixed solution.
The reason you may need to bump your numbers back in line when using All for Reef is because it uses a Formate which has to be broke down by bacteria first before it is usable as Alk and calcium for corals. Things can get off a little bit. But only in the beginning did I have to adjust anything.
I didn't mention dosing magnesium separately but you may need to, it depends on your salt mix really. Some are pretty high and magnesium gets used very slowly. Still it's a major element you should keep an eye on and be prepared to dose.