There are things which you learn easily and then there are things which you learn the hard way. Even though I knew that a my own domain name with paid hosting would be right choice, I opted for blogger because I wanted to test if it is even worth. I think the message is clear- Internet has got huge potential but you got to be patient with it. So after one year and more than 200 postings I have learnt and made mistakes which I would like to rectify in my new blog (chilli flakes would become more interesting though). The points below would answer many of your questions and can clear your doubts too.
1) Start with your own domain name even if you are experimenting. It would cost a max of $70 for a year.
2) with domain name and hosting you would use CMS tools like wordpress and hence get knowledge at early stage.
3) There would not be loss of any posting because almost all of your posting would be available.
4) As the site gets old, with age it earns up a page rank. Though there are many techniques involved but it helps to start early. The site rank cannot be transferred.
5) Adsense is great pull but it is worthless if you have low traffic.
6) Refreshing your site continuously wont help in traffic. At most it will distort numbers.
7) Content is always the key. Its nice to see your postings running up the charts.
8) Quantity of blogs is also as Important as quality. Its like giving many doors or options to visitors so that they can reach your site.
9) Building traffic is not easy. Its a hard work all the way.
10) you need to work hard and learn techniques to increase traffic. Sitting in isolation wont help.
11) Page Rank is very important. It is a door which will open many earning opportunities.
12) Finding niche is very important but it is not only thing (so dont get upset). You can make your posts interesting to bypass this law.
13) If possible try some pictures, videos etc to give lively look to your blog.
14) Making money is fun and your own domain name with good rank will give it real boost.
15) Set target for your site and money would come as a by product.
Internet is huge opportunity and many people are making tons of money from it. If money is not your motivation then also keep blogging because the hobby would turn profitable and meaningful at time when you would need it most. Its a big project which will run for years and you need to be patient and diligent with it.