Transferring USD into a TFSA

I am currently working in the US but maintain my residency in Canada and file with both the IRS and CRA. I have accounts with both Questrade in Canada and Robinhood in the US.

I wish to transfer my holdings in Robinhood to my TFSA account at Questtrade. I am not sure about the particulars, but have two major questions

1. The contribution room for my TFSA is stated in CAD. If I transfer USD to the TFSA, how does that affect my contribution? Is it converted at the market rate?

2. When transferring automatically, i.e. using Questtrade to initiate the transfer, will I have to pay capital gains on my holdings at Robinhood?