Hi and welcome! I'll try to help you with your enquiries:

Q1. Can i be able to use my own laptop or tablet on board at anytime given to all of these routes i be on ?
You can use your electronic devices at all times excepting during take off and landing.

Q2. Can i recharge the laptop & tablet & video camera with the my own cables and charger that comes with it on board?
In the Finnair/Flybe segments no. Not sure about Qantas though, they may have an USB connector for your use so you don't need any adaptor. As in Singapore you will have probably a few hours break you might want to charge your devices there as well. In Singapore Airport, if I recall correctly, you can use diverse types of plugs.

Q3. is it good to choose the speal meal or its not that important to choose anything?
If you don't have any medical/health/ethical/religious preference, then your standard meal will be fine. Don't expect great meals from Finnair in economy, but the offering of Qantas is significantly better.

Q4. Can i use my hair straightner to style my hair and brush my teeth ? and put hair spray and perfurm if i need to?
You have to be aware of the liquid restriction: max 100 ml containers, carried in a plastic sealable bag. You can use hairspray and perfume if you want, provided that you follow those limitations. Toilets in the long segments are slightly bigger than in European/regional aircraft.

Q5. Does this airline actually provides free newspapers and tablets with games or not really as there be my personal tv screen infront of me where i can choose 100s of channels?
I thing Qantas doesn't give newspapers but Finnair usually does in the long haul. Most of them are Finnish (Helsingin Sanomat, Iltalehti...) but they also have Helsinki Times which is a local paper in English.
There are personal screens across the long haul fleets of both carriers but the offering varies. Some Finnair aircraft are really old and feature only a small selection of films in a tiny screen. They also have some games there but very basic and desperating since the screens are not very responsive, but they don't provide tablets.

Q6. Is there an actual telephone on my seat?
You might have it in some aircraft, but sometimes doesn't work properly. You can swipe your credit card there but the rates are usually quite high. In Singapore and in Helsinki airports you have free wifi that you may use for a Skype call. At Singapore you will also find free computers.

Q7. Will my headphones will be able to plug it in the socket?
Both carriers provide free headphones (Qantas) or earphones (Finnair) that have a double connector (so you cannot use them outside the aircraft) but not sure if you can plug your own. The two connections are supposed to be left and right.

Hope that I have answered your questions. Its a long journey and you will end tired of being fed with airline food, but hope that you enjoy your trip. I was recently flying from New Zealand to Finland via Sydney and Singapore (Qantas and Finnair) so you might find useful my trip report:

http://www.flyertalk.com/forum/trip-...-qf6-qf47.html

Cheers!