Change contact form design in 7.1?

Site URL: https://smilodon-ocelot-my5f.squarespace.com/contact

Hi,

How do I change the look of my contact form?

I want to make the following changes in both desktop AND mobile view:

1. Change words under name boxes to just "First" & "Last" instead of repeating the word "Name"

2. Have the option of making all words caps with control over the letter spacing.

3. Turn the boxes into an underline only apart from the "Send" button.

4. Make sure the send button is NOT curved in the corners. Capitalise "SEND".

Similar to this (only no grey background):