No don't think it's possible.

There are operational upgrades where people get upgraded because economy is oversold or something along those lines. I got it on Emirates some years ago (economy to business) and on MH many many years ago. It's much more likely to happen if you're flying alone.

No real way to guarantee it though, it happened to me twice in > 20 years of flying so don't hope much.

Possible. Join the bidding for business class. Offer how much u think worth to upgrade to business class. Higher offer and availability of seat will determine your success. The website also show what the previous bid amount that success.

How is the bidding system? Can share more on it?

if u r only keen on upgrade to biz class, best to fly Airasia X and get an AirAsia-Citibank Platinum card. Free upgrade every time unless the seats are fully sold out.

plat card only. just check-in at the AirAsia X counter, show the card and get ur free upgrade. this benefit is stated in black and white on both citibank and airasia's website.

I've never been in a FF program that allows a person to to accrue miles in another person's account. Each ticket can only collect miles for his or her own account, including Enrich so to me the email is not surprising to me.

There are some programs that allow a family to pool miles eg. Avios but I've not heard of Enrich doing this.

You can redeem miles for another person from your account, but accruing is different.