Re the fuses to piggyback onto - from the PDF diagrams above (Polo 6C 2014-2018), I'd gone for Vcc => fuse 5 (driver's door control unit) and for Acc => 23 (washer pump)...are those OK?
I got a couple of tap fuses but when trying to fit them, they just don't seem to fit well around/over the existing fuses (i.e. the blades don't sit nicely due to the tap'd fuses pressing against the existing fuses). For other's who have done this, did you use the standard size fuses to piggyback? Or would it be better to go for the mini fuses? And if so, which ones would be good ones to use? Possibly Acc => fuse 36 (heated front seats), Vcc => fuse 17 (anti-theft alarm sensor)?
I'm sure I read somewhere (though can't remember where!) that it's best to use fuse slots that are rated 10-30A - is that true?
Sorry, that's a lot of questions in one post!

Thanks