One can be an alum of many places if you just keep going back for more degrees
If you are trying to pack light, being willing to do laundry is key, and packing pretty much only pieces that go together (which is why I like Janice's "Whatever's Clean wardrobe templates when I try to pack light) I'm not making a judgement on packing light or not - I can and have done both, depending on where I'm going & what I'm doing.
That said, it's not impossible to pack light and still be able to survive 50-90 degree temps (30-90 might be a little harder - for me at least)
If 50 is pretty cool for you where you want a jacket, bring one (I would be ok with a cardigan over a tee - maybe a long sleeve tee if it's windy - but I also travel with 2-3 scarves and those usually keep me as warm as I need to be) Shoes you can wear with socks (for temp or for walking) is an individual issue to consider. Most of the time I wear walking sandals that can take a beating and keep going (my favorites are dansko that aren't made any more and I'm screwed when I finally kill them!) If the Superga shoe you posted fits you and is comfortable for lots of walking - go for it. Sneakers of all types are all over the world (stylishly so) on people of all ages. I personally don't wear sneakers often - they're hard for me to fit well.
I try to bring 2-4 tops per bottom - much easier to wash & dry a top overnight as needed too. Although it would be logical to bring skirts instead of dresses, I prefer to wear dresses, so that's what I pack. And again - if I need to do laundry in the sink to dry overnight, that's fine.
Have fun preparing for this trip!!