Number 1 is mostly correct. You cannot give a reward to a post or comment that is over 7 days old. Actually the cut off for a reward is 12 hours before the 7 day mark.
Number 2 is a little correct, in that you have a limited amount of rewards available and every full power upvote reduces your voting power by 2%. You also recharge voting power by 2% every 2.4 hours. So if you only give out 10 full power upvotes every day you will stay close to full power.
You can see your voting power level here: https://steemd.com/@swissclive