If I add my best friend in my second hand car title along with my name, as joint tenants with right of survivorship, is this considered a gift? If so If fair market value of car is 17000$, then 17000$ is gift amount? Or 17000$/2 is gift amount?
Suppose a father buys $10K of stock which appreciates to $15K. Then that stock is gifted to his son, who eventually cashes out when it appreciates to $30K. Does the son owe capital gains tax on a $15K profit, or does it need to be calculated as a $20K profit?
Great question, in your example the capital gain would be $20k as you need to use the donor's basis to calculate the gain. There's a great example of this in the IRS Publication 551 using land instead of stock, but it is the same idea. Search "Property Received as a Gift" www.irs.gov/publications/p551#en_US_201812_publink1000257002
What about the receiver, is there any limits on how many gifts I can receive from different people? Let's say 3 different family members give me 15k each, do I need to report that?
No limit on how many gifts you can receive. The reporting is always the responsibility of the person giving the gift not the person receiving the gift.