How to Create a Light Wallet and Light Bitcoin Node, and run it on Mobile? For example, instead of using my laptop to run bitcoind...how can I run bitcoind on a smartphone to create a light bitcoin wallet?

I understand hashing may drain battery, but is this possible? If so how?

I read somewhere a client is considered "light" if it doesn't download the whole blockchain, but just communicates by sending headers.

Thanks.
If you're looking to mine on your phone, it's literally useless. The hashing power on these devices is so low that you'd probably need a very large amount of phones (around the thousands) to reach the hashing power of a single ASIC machine.

Also, storage is an issue because a Bitcoin node needs all of the blockchain data (around 17gb as of today), so you'd need a high-end phone that has a large amount of disk space.