OK, firstly welcome to the forum (and the wonderful world of woodturning).
Now a few attempts at answers. The Y-shaped pieces are called crotches, and they are popular because these are often areas where grain develops into ripples and other visually interesting patterns. However, for a total novice, you should ignore these for now.
The species is a little hard to tell from the picture, but at a guess I'd say it's ash. If you just leave them as they are, you will have perfectly good firewood in about 3-4 years.
Yes, converting green wood into usable timber for woodturning is a process of its own, but it's not that hard. However, you will need a chainsaw (and all the associated safety kit), or a very large bandsaw.
There are now two options: green-turning or drying.
Green turning is fun, but messy. There will be water flying everywhere and the shavings are wet, so wherever they touch metal, there will be rust. Green turning is useful for bowls and hollow forms, but completely pointless for most everything else. If you want to keep your wood in a green state, you need to wrap it completely in cling film or plastic bags and seal the lot so that the moisture cannot escape. Most likely you'll also get some spalting in the process, as fungal spores are normally everywhere.
Drying takes time and a little more effort, but can produce timber useful for a very wide range of projects.
Under normal circumstances the first thing to do is split all the pieces down the middle. You need to expose the pith, as this is normally the area where the cracks start, and only if you give the wood the option to shrink on its circumference do you have any chance of avoiding that. The only time you would not do this is if you were to green-turn a hollow form. Given your level of skill that is not for you right now.
Once the logs are split in half, decide on the blanks you want (or can) make from them. bigger logs may well yield some nice bowl blanks, smaller logs give spindle blanks. At any rate, once you've cut the logs into the sizes you want, you MUST seal the end grain, either with wax or PVA or end-grain sealer (if you have money to burn). Wax is messy, but tends to yield the best results. PVA is cheap, but can result in some mould growing. In any case, make sure your cover is over the entire end grain and roughly an inch along the side grain.
Probably best to find your local club and become a member, or go for some tuition from a pro for the actual turning.
