Wow! You have lots of questions there, which one is the most important to answer? I'll answer questions that I can answer, let's straight to the point.
Those are with 3rd party right? Are those safe?
Third parties can be safe or unsafe, depending on the entity that looks after them. If that entity has high credibility, there's nothing wrong with entrusting our tokens to them for staking.
Now if someone is going to hold an altcoin and can stake it, is there any reason not to stake it? This is assuming you already bought that altcoin a while back and don't plan to sell it.
Sure, if this holder has a speculative type, it's not good for staking, because we never know whether the tokens we're holding will rise in the near future or not, I'm one of the people who has regretted staking, I staked Oasis Network (ROSE) and a few weeks later the token price up 3 - 4 times, I was helpless with my staking because I couldn't sell it and had an unstake period before the token was returned to me.