The chewing hands and droolong may well be teething. How much milk is he having at the mo, and how long is he lasting at night between feeds? This is normally the best indication of whether or not he is ready, if he starts going less time at night, or needing more frequent feeds. Noah was on 8 9oz bottles of hungry baby formular a day when we had to start weening him, just cause we couldnt make our bottles any bigger!!!
When you do start always introduce one flavour at a time, then you can discover what he does and doesnt like and if he has any reaction to anything. You will find to start with that when you put food in his mouth that he will push it back out with his tounge, so it will take a while to get food in him. This is because they are used to sucking milk which involves pushing the tongue forward, and it takes them a little while to learn to push food back with their tongue.
When you introduce solids for the first time the lunch time meal is best, as they are not ravinous like first thing in the morning, and you have the time to sit back and take your time, some people give half a bottle first to take the edge of their appetite, but personally I prefered to start with the solids straight away, as Noah didnt like me taking a bottle away from him half way through. Always start with fruit or veg, easiest to cook some up yourself and then stick it in the food processor, and you can freeze these in ice cube trays then just defrost any combination of flavours as and when.
Hope this helps, have fun!