Also is there any guidance on whether its ok to dose two part as well as kalk?
Go with the kalk. Unless you have a heavily stocked and mature sps tank the kalk will be enough to maintain your Ca and Alk. However, it might be a little hard to dial-in your proper kalk dosage so you might need to "top-off" so to speak with a 2-part once a week to maintain your levels.
Start by getting your levels where you want them by using 2-part.
It is typically recommended to begin with 1 teaspoon of kalk per gallon of rodi. See what this does for a week. If your levels dropped after 1 week then adjust with 2-part to get you back to where you need to be and increase your kalk. Try 1.5 teaspoons per gallon for the next week and test again, etc.
Keep in mind that kalk is saturated in water at 2 teaspoons per gallon. If 2 teaspoons per gallon doesn't work, then you can supersaturate the suspension by adding vingar.
As an example, in the summer months my tank runs hotter and my cooling fan speeds up evaporation so I am just fine with 2 teaspoons/G. However, in the fall, winter and spring I evaporate less so I need 3 teaspoons/G which can only be accomplished by adding vinegar. (To supersaturate you will need 15ml of vinegar per 1/2 teaspoon of kalk)
Last consideration; most 2-parts also include trace, kalk does not. So you might want to consider dosing a trace supplement or keeping up with 10% weekly WC's to replenish.
Hope this helps.