Both of this coins are very good. They are the leader of crypto market. If you have enough money you can invest invest 50% in BTC and 50% in ETH. It will highly decrease the chance of loss. So if you have a good amount you should invest in both of them.
Always Do your own research before investing.

I like Polkadot more than LINK. Because Polkadot has more real life use cases than LINK. Polkadot solves all of the problems that we face with ETH and also has all the features of ETH. So i am very excited about Polkadot because if its able to attract the people's it can go a long way I think.

I also agree with you. Never borrow money or invest the any amount  of money which loss you cant bear. Only invest the amount of money of which if you lose all that money it will not have a big impact on your. Crypto industry is very risky so first learn and know more about crypto before investing

I am big time follower of ethereum from initial days i was holding ethereum even the price less than 100$ and also i was holding ethereum at the price of 1500$ . But based on recent development i am highly speculative ethereum price after 2.0  release . Once POS introduced the problem of scalability will be solved  Maximum supply will be fixed . So i am slowly investing on ethereum from my savings part by part reasons are below
1) Inflation in global curreny or fiat curreny ( ehtereum and bitcoin is best alternative invetment solution )
2) Ethereum is the best Smart contract creation platform holding major DAPP's in market
3) Real world use case

I also agree with you. ETH is the second bets cryptocurrency after BTC. Its smart contract creation is the best feature of this. But because of its low transaction speed and high demand the transaction  fee is increasing which is the onlybad side. I hope also this will get correct by tye time ETH2.0 goes online and the gas fee decreases.
It has a very bright future.

Both ADA and LINK is good crypto. They have a bright future. But ADA is performing better than LINK from some days if you want a good profit within a short time you can invest in ADA
Do your own research before investing

You can use wallets like
Exodus
Scatter
Wombat
Guarda
im Token wallet
You can make your own address from bloks.io

This time the bull run is much much bigger than the one of 2017. At 2017 when people were making money by trading many people started investing blindly this time most of the invetsors have vast knowledge of crypto. Big payment systems like PayPal and Visa started accepting crypto. Al of this having a great impact on the market. This time the bull run will be much bigger than the one of 2017

XRP is always my favourite coin because of its such a strong team and its revolutionary ideas. It is one of the most reliable coin for long term other than btc. I always recommend people to buy xrp for long term profits. Go on Ripple(XRP)