I can't remember if it's last year that they have revised the redemption award. Right now, if you are redeeming SQ ticket to SIN using your UA mileage plus miles, you only need 20,000 miles to do so, because they consider both places to be in S. Asia.
Both UA Milleage plus and Marco Polo Club ( CX) have different member levels, e.g. primary, silver, gold, platinum, diamond.
I am a UA Milleage Plus primary member ( blue card)I just redemed a free ticket from HK to Tokyo by UA for 20000 miles, but if I redem a ANA ticket I need 40000 miles. Miles you need quite depends on which airline you choose.
e.g. in UA milleage plus, travel by UA, from HK to sing need 20000 miles, from HK to Seoul need 20000miles, from HK to Tokyo need 20000 miles (both travel by Korean airline / UA)
How to earn miles : airticket, HKBC Cards.
I know , some airline e.g. cx, will use your miles to upgrade you membership.
For UA, if you need e.g.1000miles, 200 miles for redeem ticket, you can BUY miles from the internet.