you should wear a tank top of any colour depending on the colour of the sweater.
If its cold out, wear a longsleeved shirt. If not, then wear a plain T-shirt.
a shirt or an undershirt
Jeans and a sweatshirt. Anything comftorable and warm.
no, but if your going in public, you should wear a bra,
It's fine to wear your boyfriend's sweatshirt at 13 if both of you are comfortable with it. Just make sure to communicate with him and respect his belongings.
Yes
you are weird
Maybe you should wear Capri's with a sweatshirt and maybe dlipflops or sandals. Or even jeans because of if there is wind. I hope I answered your question!
Medium
Usually I wear a sweatshirt that is the team on the SnapBack or something the same color like I have a celtics SnapBack and I don't have a sweatshirt but I wear a long sleeve gray with the sleeves up and some jeans.
If you wear a L size and you want to buy the hollister sweatshirt get the XL size.
socks, sweatpants, sweatshirt, sweater
40 degrees isn't that bad, so you should wear a sweatshirt over any t-shirt and some pants and you will be fine, great if moving around.
small little coat or jacket and jumper, it's not that cold.