You seriously
should do some research before ask about common/topic.
https://en.bitcoin.it/wiki/Colored_Coins should answer your question.
The most popular colored usage that i know is Tether (USDT) through Omni Layer protocol.
And then later how to extract that data for use?
If you know the Transaction ID, just select the output which uses OP_RETURN and encode/decode it if necessary.
and how to increase that 80 bytes size?
1. Change soft-limit on source code
2. Make hard-fork and make sure majority agree with the changes
and up to what size increasing possible?
Should be very big, but limited to limit with size that database (LevelDB or whatever database your client use) support.