If you exceed the suggested speed of a corner, your car will start to overheat, meaning you'll gain Heat cards. Push too hard beyond the limit and you risk spinning out, which can severely impact your position.

The rules state that you adjust your gear each round, but don't specify restrictions on gear changes. However, since you must play a number of cards equal to your current gear, dramatic gear shifts would require careful hand management.

Heat cards start the game in your Engine spot (not your deck) and represent engine heat buildup. Stress cards start in your draw deck and represent mechanical stress on your car, diluting your hand with less useful cards.

The rules indicate that your gear 'dictates how many cards you play that round,' suggesting you must play exactly that number. Playing fewer cards would mean moving slower than your gear allows.

Yes, Brake cards specifically have 'variable Speed values you get to choose from,' allowing you to select lower speeds when approaching corners to avoid exceeding their speed limits.

Heat cards can be played for their speed value and help you move, while Stress cards typically provide no speed benefit. Generally, you'd want to play Heat cards over Stress cards when possible to maintain competitive speed.