07 x5 4.8 Winter tire question.

[DANTENING]

Hello Guys:

I have a 07 x5 4.8 sports pkg with 19' rim and I'm considering buying a new set of 18' + snows for the winter. Here are some questions and plz help out:
1. Is aftermarket BMW replica really not good? I've heard that they crack on highway causing terrible accidents.(From dealer, not sure they told me that just want to sell me the winter tire pkg at 3,500+ tax..)
2. How do I know if I've got TPMS on my current 19' and all season RFTs?
3. If I'd go with replicas, do I need to buy TPMS and put them in with snows?
4. I want to buy a set of spare tire and jack kit,(Canada model don't have it..) where's a good source? Dealer doesn't have it for sale.

Thanks for any inputs, and happy holidays