Start offering solid food now, and see whether your little one will start eating it- you'd be amazed at how young they will start eating solids- I rekon he'll show at least some interest now
. Hills tinned kitten food is great, as are their kitten biscuits- perhaps my favourite brand. Thing to watch with kittens is that its essential they're on a good complete diet, to support their growth. If the nutritional content is in the incorrect ratios, or crap quality products were used and the cat cant actually absorb it, you can end up with issues. So, perhaps start by offering a decent quality tinned/kitten wet food, and then offer dry food. Another thing with kittens is that because they need a lot of energy and other nutrients to grow, they often cant physically eat enough wet foods to get adequate amounts- hence why biscuits, being a dry and concentrated form, can achieve this much better, if that makes sense. Once onto a good quality kitten diet, milk wont be needed at all
And yes, cats are typically extremely easy to toilet train. They instinctively want to dig and bury their business, so if you simply place them in the tray they quite often just go to use it. I usually start kittens in a small room, such as a single bedroom, where they know the litter, food and water are- this becomes their 'safe' place and they learn quite quickly. When you later let them out to roam the house, they still know where the litter etc is, and if they get frightened they run back to where they know is 'safe'
Anyway, hope this made sense. Just what works for me, and from experience