When you go long you pay interestWhen you go short you get paid...

When you go long you pay interest

When you go short you get paid interest.

it evens itself out in the end.

Brokerage is usually very low. The spread mimics the market bid/offer price, except for overseas shares (CMC is quite accurate on some UK shares).
But of course, even a normal market spread works in the CFD providers favour.
If the bid/offer is $1.00/01 it's not like you can buy at $1.00 and sell at $1.01. You need to buy at $1.01 and the stock needs to move above that price.

Buy and hold is possible with CFD's but usually becomes a short to medium term trade anyway because of margin. Good to keep half the account as margin buffer.