If a friend ows you 0.1 Btc from Dec 2016...

First you have to make sure he remembers the private key, then you need to make sure he remembers you.   

Here is an idea: Get a few of your crypto rich friends together, buy an island, call it CryptoWorld. Then issue visas to the people who want to trade cryptocurrencies, so that they can visit your island and trade cryptocoins.

You just saved the Crypto World!  

If alien means that some one is different from most other people, we are all aliens, since each of us is unique.

I agree with you. People can end world poverty, sometime in the future if they want to. Bitcoin is just a tool, still needs to used by the people who has the will to do that.

I want to transfer my BTC from one address to another (both are mine), how do I avoid paying the transaction fee?

Control your pace if you are chasing tails in the crypto space, things move really fast.

Bitcoin is a software, it will last forever, even it means that it only lives on a CD or a hard drive.

The question is: Is the value of bitcoin going to survive after 100 years? After 100 years, will it still be valuable?

I don't think it is stoppable. If the old bitcoin protocol become outdated, it is up to the team to come up a new bitcoin protocol, and port the bitcoin holding records and wallet addresses to the new one. It is a blockchain based ledger, like a notebook. So if the old notebook run out of pages, simply create a new one and port everything to the new notebook. Hard fork, soft fork, exchange coins and etc, it is a free market.

Where do we find info about high potential coins?

How to do micro payments with bitcoin? The transactions need to be verified on the blockchain, but need to minimize the fees.

Bitcoin is facing many challenges, its outcome will depend on whether it can reinvent itself and adapt to the market.

Many other cryptocurrencies are making good progress, and make become leaders in the market. The entire cryptocurrency ecosystem is still at its infancy.

It depends on whether you are looking for short term profit or long term investment holding. Some good ICO project can be good long investment, especially if they already have products in the market.

What are the reasons for investors to buy in an ICO if prices often drop after the completion of the ICO?

Today's Cost per Transaction (USD) is $124.76.
https://blockchain.info/charts/cost-per-transaction

It is not feasible to pay people with bitcoin when the cost is so high.  I wonder whether they will be able to reduce the transaction cost.

Cash is the king. If bitcoin waives its peer-to-peer transaction fee, it may have a chance to win the title. 

Women are 35% more likely to live in poverty than men.

Two‐thirds of minimum wage earners are women. One in seven women lives below the poverty line. More than
half of all children below the poverty line live in families headed by women.

Women-owned businesses only account for 4% of all dollars lent to small businesses each year.

Female CEOs get only 3% of all venture capital.

https://kairoscenter.org/wp-content/uploads/2017/02/Poverty-Fact-sheet-Jan-2017.pdf
https://www.fundera.com/blog/the-state-of-online-small-business-lending-q2-2016
https://www.inc.com/magazine/201611/kimberly-weisul/new-face-of-funding.html

If there is any place where women could ever hope for equal funding opportunity, it would be in the crypto world.

Please help and support these women. Please don't block their bitcointalk topics, reddit accounts, copycat their projects, hack their websites, hack their emails, leave bad comments, or do other things to block their projects. Please guide and support them instead. Above all, please help promote and fund their projects.

Women lead projects may not sound as grand as men lead projects, but are often more practical, and could be great for long term investments. Women's projects quite often focus on people, especially those who need help most, children, seniors and communities. The money invested in women lead projects may spread wide, last a long time, and generate abundant returns in time.

Interesting. The ratio probably is 97:3 for male and female here.

The questions is: if women actively involve in the crypto world, will they get the support they need? Many talk about it but few gives tangible help.

Where can we find more API information on this?

Among bitcoin, bitcoin cash, bitcoin gold, and litecoin, which one is best for investment?

The spike in bitcoin's transaction fee is hindering its liquidity. The question is: can and will bitcoin maintain a low transaction fee regardless of its price?