Just stumbled upon your post by accident and glanced through the replies so far - so apologies to anyone if i've overlooked some nuance. A few thoughts that i had:
1. agree with most people that HKD25k/m is very little; but many locally sourced jobs are at about that rate. you generally will need to live conservatively and budget accordingly, but a lot of the population here lives on less (and does not live the typical wild west lifestyle)
2. look into housing in sheung wan, wanchai, causeway bay and kowloon - everywhere. public transport works great here and is cheap, so may be a good solution. if you are committed to going out etc., you'll make it happen. everything is so close here compared to LA or the US generally. there's no craigslist in hong kong - a lot of people rely on local rental agents to find their first place - usually just by walking around the neighborhood they want to live in. looking on these forums helps too.
3. u say u r american? regarding the tax back and forth people had - as an american citizen you will be taxed on worldwide income so you need to pay US taxes AND HK taxes. You will get a credit for local taxes paid but you still need to pay them - you should discuss with your employer about appropriate withholdings - if they do that. there are tax benefits to living abroad though - as you may know - your foreign income exclusion will probably obviate any need to pay US taxes but you should consult with a tax advisor or friend if you have one to drill this down. it can help you save.
4. do you speak chinese? i think this is a consideration for potential job prospects in the future. i'm a laywer in HK now and have a lot of friends who have been looking too - it's a tough market but chinese ability really gives you an advantage over other people. if not, you can also look at singapore. You may also consider discussing with a headhunter locally to try and get you some leads.
5. for food and drink generally - for a single person, i think eating out at the right places is probably cheaper than buying food, cooking etc. and less time consuming. there are so many very nice cheap local food places - if you like chinese - that will not hurt your budget at all. even some western places cater to this. i've been on a HKD40 budget for lunch and it's easy to live on it. you can get a bowl of outstanding wonton noodles for HKD30. it all just depends where you go and what you want. for going out, if you really like to drink, drink more from teh convenience stores first then join later to save some money, or find happy hour deals. some nice clubs have great happy hour deals with buy one get one free and free food - HKD100 for 2 drinks and dim sum buffet is not bad.
all in all, it will be tough but doable. plenty of rich people in HK, make some good friends and you'll be fine ^^