'Don't travel during National holidays!'

Plan your trip before or after Oct.'s holidays. Whole China travels on National day holidays!

The cheapest hostels you'll find in Mong Kok/Tsim Sha Tsui. Just walk on Nathan Rd. toward the Sea. You'll find 'very scenic' million hostels spot in 'Chung King Mansion'.

If you're looking for more up-scale housing look at Agoda or just Yahoo-gle 'Hotels in HK'.

'There're 7 brazillion people live per m2 in HK, and personally that's not my 'cup of hong cha'.

Weather in HK is very similar to S. Florida, year around. Hot and soggy.

Hong Kong does work during public holidays, but is better outside it. Since I am just a ferry ride away from HK, I've been there a couple of times to get away from the holiday hell in the mainland. 

Don't go to The Peak unless the weather is particularly clear. (and don't go there by taxi, either take normal bus or The Peak Tram) 

October weather can be anything from hot/humid to pretty warm but nice. The main problem in HK is that a lot of the time you are between tall buildings and fresh air is not just blowing around you. By the habour it is generally more bearable

If the main purpose of the trip is to get away from the mainland than stick to HK island and stay away from Kowloon as it is swamped with mainlanders and especially so during any holiday. Its a little pricier but research and book rooms early with save alot. I wouldnt just show up looking for a room as they can be hard to come buy and far more expensive.

A week or so is a looong time for HK, especially if money is a concern. If you dont have much cash. Book a room on lamma island for a day or two. Some pubs. A nice beach, more relaxed. If you have extra cash then dont waste the opportunity to see macau while you are there. Its a fun place. One day and night is more than enough.

If you cross the border by foot use the Futian checkpoint, not Luohu (which is close from the train station), you will avoid most of the crowd and the smugglers.

Cheapest clean and safe hostel (not hotel) is YesInn, private bedrooms start at HKD230/night, they have branches in Kowloon, Causeway Bay and Fortress Hill.

Otherwise you can spend the night in one of the many hostels at Chunking Mansions where all the illegal Indians and Africans of HK also live, including drug dealers and addicts among them.

Hong Kong Island is more international, Kowloon is more Chinese, in the first you will find luxury shops, restaurants from all over the world, clean streets, more skyscrapers than you can count, the population is mostly made of HK natives among them business people/managers/urban youngsters with high fashion sense, there are also many expats from first-world countries, ... in the last you will find crowded streets (more crowded than in any Mainland city), small dirt cheap restaurants, the population is made of lower class HK natives (workers, ...) and Mainland Chinese immigrants but also immigrants from less developed countries, many shops selling "fell from the truck" or fake products, ...

Both side are great in their own way, but if you want to get away from the Mainland's madness for a week I advise HK island, Kowloon is not much different from Mainland cities nowadays.

Thank you everyone I really appreciate all the responses and yes my quest was to escape the mainland holiday chaos and I am thinking if the holiday mayhem overflows into Hong Kong then I might just give the trip a miss for now. Although Hong Kong Island sounds and looks quite nice as even a 5 day trip would be a welcome break.
I usually never leave my apartment during national holidays and am assuming all of China is just heaving with people out and about. Would fellow travellers suggest any other countries in the South East Asian region worth a weeklong trip as my colleagues are pushing for Singapore but I am assuming that will also be pretty crazy?

Everyone should do the following!  Touristy?  yes definitely, but also a big part of HK history.  :-)

http://www.thepeak.com.hk/en/home.asp

http://www.hongkong.net/transportation/ferry

If u stay on Kowloon (TST, Mongkok) you can maybe wander around Temple Street Night Market.  wander down some of the little alleyways at the north end if u want to see the illegal ivory for sale. weird to see, but darn sure don't buy it.

I strongly second the advice about never traveling on National Day.  Unless you live in Shenzhen or Guangzhou, you are asking for trouble.  Also National Day in Hong Kong is just like being in the mainland.  So many mainlanders travel to HK on holidays, forget it.  Finally, unless you have lot of money to splurge, forget hotels in HK.  Go to this website  https://www.airbnb.com/     Why pay 400HKD for a cramped room when you can have a whole apartment?  I no longer pay for hotels in Hong Kong unless it's a 5 star luxury vacation.

Have fun.

Only travel by air during national holidays. If you try to  go to HK, you will be accompanied by a few million mainlanders.

Lockhart Road on HK Island for bars. Expensive, but so is almost everything in HK. It's a while since I have been, but also on Lockhart road is Ebenezers Kebabs. Fantastic.  It's also where the boy racers meet in their Skylines and 911s.

Kowloon, there are a couple of Irish bars at the bottom of Nathan road.  Paddy o Neils on Nathan road itself ( On the bottom, left hand as you go towards the avenue of stars and Delaney's which is just off Nathan Road on Peking Road.  Again, these are pricey but if you want to splash out on a full Irish all day breakfast

Symphony of lights seen from the Avenue of stars is a must.

If you can travel from GZ, it might be worth trying to get a ticket on the GZ to HK through train. That way you only have one train load of people to deal with at emmigration/ immigration.