'14 Octavia Elegance 4X4 haldex Queries?

Morning All

so recent purchase I mentioned has now done its first 1000 miles in my hands, but not before some teething issues:

Initially no 4x4 system working and classic only 1 half of the heater working, took it back to the trader who sorted it after pointing out the forum posts about both issues ( but not without some "i know better than you" attitude 🙄  

in the need Its ended up with a new heater direction valve and allegedly reconditioned haldex pump and oil change allowing the 4x4 system to now work. 

funnily enough it seems I ended up with some fresh coolant too  so it may of had the matrix flushed through too ( still with the "Mitt Silica" bottle though)  but also some windscreen stone chips and a slight whine from the rear end which wasn't there before i got it back 🤨

Given his attitude and the distance from home I'm not bothering to take it back to him again but fully suspect its either had a the recon  pump and oil change as he claimed to fix it and the took it rallying resulting in the screen stone chips and whining noise starting  or they shoved a second hand diff and haldex system under the back end which hasn't been looked after.. 

either way I've got some questions as I want to look after the back end and make it last.

Firstly as I intend on keeping it what spec oil and service kit will I need for Diff & Haldex as I can do that myself? 

Secondly I know from my time with other haldex equipped cars that they self test when pulling away to check the road grip levels, my old freelander 2 that it would chirp at low speeds when maneuvering then only worked  when required.

This will sometimes react in the same way yet other times it will test with some soft thunks as it kicks in the rear wheels which can go on up to 10-15 mph, is this normal or the symptom of something that needs a service? 

Thanks