Title transfer and gift tax

[Steve Tom]

Long story short, my in-laws have helped me paid off our first property 8 years old, so we could saved enough money to purchas our current house and turn the old house into rental property.

Now that my in-laws are in their 80s, they would like to have a place of their own to retire to. Currently they are living with my sister-in-law in California but not in a very good term with her. 

Here are a few questions I have.. 

1. Can I just give them the old house by transfer the title to them?  (Since they helped with almost 60% of the finance of the house by emptying their saving)

2. They are not wealthy now, sicne both are retired and only source of income are from SS. If I transfer the title to them, will that affect their SS benefit? Also they have to report to the California State government?

3. Do they have to pay gift tax? 

4. In order to help them, we plan to help pay for the annual property tax. Woudl there be any tax consequences for us and them - If they are owners after the transfer and we helped pay the taxt?

5. Another route my wife is thinking, is to transfer the title to her sister, and have her manage it all. Woudl thsi be easier than giving to the parents?

Thank you. However, the more I think about this, the more questions I have and definitly need advices.