Milan to Varese travel

Hi all, I'm arriving into MXP at approx 4:30 PM local on September 2nd (Wednesday) and need to get to Varese. Planning on taking a train with my luggage but am looking for help on transportation and timing.

Should I book a train ticket ahead of time from MXP (and which train station?) or will I be OK to purchase one when I arrive? I don't want to assume a cross Atlantic flight will arrive on time and would hate to pre-purchase a train ticket and then miss that train.

Once in Varese my friend (local) recommended getting a rental car for moving around the city and the surrounds for myself and my girlfriend but it seems most of the rental car locations are a decent distance from the train station. Is there a recommendation for how to go about that in Varese? I've heard taxi there can be unreliable.

I have done a good bit of international travel so I can certainly figure it all out but found this sub and thought I'd ask! We're doing ten days through Tuscany afterwards and are so excited, and have that portion well planned out but this initial part is a bit confusing to us. Thanks!