Each vote cost 1 Ark if I vote and after few days decide to un vote,will I get back my ARK?
I have a very small amount of ark I.e only 8k, which delegate should I vote for (top one or someone from middle) to get best results?
Good questions.
It doesn't make sense to me yet. Some delegates only share 50 or 55% and others share 75% or more yet the delegates which share LESS ARK have much more votes and voters than the ones that share MORE ARK. How does that make any logical sense???
I see two reason just from the top of my head:
1. Because they started early, and usually have one big backer/voter (probably themselves). They don't need more votes (right now). No need to offer bigger rewards... People just registering nodes need some way to attract new votes. Greed is always a good ally...
2. Some people honestly believe in backing the community and support nodes that will give a % of the income into developing services. They are not only looking for short term profit, but think of it as a long term investment...
P.S. Don't try to understand everything. You'll go nuts

Thanks again

I see, for other long-term projects, not just short-term profit-making.
I am in ARK for the future of ARK, not just profits. I believe in it.
Final question. I don't have an account with the ARK client yet (I just downloaded it but didn't set anything up) and therefore haven't voted for anyone yet. Do I have to do all this before forging starts later today or can I do it tomorrow, next week, next month, etc.?
It is however true that the sooner you do it, the more you can expect to gain from it. Early adopters usually get the best deal.