Hi Derek!
3 - Los guantes de invierno tienen velcros que se pueden pegar fácilmente a la barra del manillar de su carriola, ampliamente utilizado para los cochecitos de un solo manillar, carritos, sillas de paseo, carritos de la compra, etc.
In Spanish "carrito", "cochecito" and "carriola" can be used as synonymous, but as in English, they have a few differences: A pram is designed to carry newborns and younger babies, usually while they're lying down. It's sturdy and generally can't be folded flat. A stroller is lightweight and collapsible, ideal for older babies. A buggy can be a pushchair or a stroller, depending on who you ask.
4 - Simplemente desliza tus manos cuando quieras mantenerte caliente, saca tus manos cuando las necesites libres. Es mucho más conveniente que quitarse los guantes = here the personal pronoun "you" is translated as "tu", but if you translate the first "you" as "usted", you must keep the same in the whole sentence = "Simplemente deslice sus manos cuando quiera mantenerse caliente, saque sus manos cuando las necesite libres." Cannot change the person in the middle of the sentence, because that's incorrect. Is the same difference that exists between 你 (tu) and 您 (usted)
Best wishes
Sofía