I have not used any of the companies you are mentioning, so I can't give any specific advice relating to those, sorry, although I can give you some general advice. I spent a year in Australia and went on zero organise tours. I will be spending a year in New Zealand (WHV also), and again, I will be going on zero tours. I'm not saying that your choice to go on a tour is wrong, but they are not for me.
The first is the 'no fixed cost' with the local travel option, what appeals with the tours is that you pay so much and you wouldn't pay more, however what's the advantage of the tour buses is it mainly the assistance and being on a crew of travelers who will stick with you as well as some tours.
These travellers will only stick with you for the duration of your trip. Some may stay around afterwards in your final destination, but the majority will depart. You will then be left with a tiny percentage of the people that you met on the tour. You will meet more people staying in hostels, than what will stay after the tour ends..
You are right however, that you may be able to save money by fixing your destinations and dates, and choosing a tour. If you want rigidity and a fixed price, then a tour may be more suitable for you. If you want flexibility, and possibly more money, then taking local transport is the choice.
The second is being alone. I haven't traveled before however my friend will be with me for two months and then I will be alone. Hopefully at this point I will know the place a lot better and feel comfortable continuing to travel around on local buses if I did take that option.
This is really not as bad as people make it out to be. I went to Australia alone, and will be going to NZ alone. Once you spend 2 months with your friend from home, you may well be pleased to see the back of her. Travelling alone means you can indulge in everything that you want, whereas travelling with others, means you have to make compromises and sacrifices. It's super easy to make friends in hostels, as the majority of them are in the same boat as you, and wanting to make friends. When you get back from this trip, you will agree that making friends is very easy.
And the third: considering I will be alone, if I were to have gone on a tour bus and would like to get a job and live there for a few months, do you think a local bus could be a better option as I would meet locals who could help out and also I noted that the tour buses only go one way round.
Local buses or tour buses will not help you find a job. The chance of you meeting a local on a bus who has a job on offer is extremely slim. Your best bet to finding a job is to talk to people in your hostel, find out if they have worked/are working and go from there. I found a job through a roommate in exactly this way, and then got another friend in the hostel the same job with me also. Tour buses may say they can help you find a job, but I am quite dubious of this. They will probably have access to a job board or something, although most hostels have job boards so I wouldn't worry.

