In reality, the only real difference is storage space and speed. The SSD will be much faster than the HDD, but at the cost of low storage capacity. There are some claims to power savings with an SSD, but it's a massive debate on whether it's actually true or not, and, to my knowledge, no one has really proved they improve battery life.
I would go with whatever suits you. If you want to be able to do things fast, get the SSD. If you need to store a fair few things on this netbook, get the HDD.
No, not at all-- depends on the SSD, i.e.SLC vs. MLC technology. Suffice to say, that MLC write speeds are abysmal. Better know which memory technology the SSD employs. If you care at all about performance than you make sure to get SLC, but chances are you might not be able to afford it in capacities above 16GB.