1. no not really as long as you are hygienic and put them in properly. If you dont put them in properly you might accidentally scratch your eye, let infection in etc and if you arent hygienic, well again your eye will get infected.
2. Yes i feel it has, you have a wider field of good vision, its probably pretty much what it feels like to have normal eyes, i feel more confident and attractive and "normal". I guess that sounds pretty stupid, but i feel like strangers treat me different when i have contacts in compared to glasses so either i actually am more attractive to people, or i have more confidence by thinking i am more attractive and people react positively to that confidence, i have no idea which it is.
3. It doesnt, i guess its a little bit odd if you think about it, and a couple of times people have barged in while i am doing it and i am like "WTF iam sticking something into my fucking eye here, can you atleast knock and not surprise me like that?" its not like putting in a retainer because you need to respect your contacts more than that and do it properly every time, but yeah its very easy, just slip them in, blink a couple of times and go on your way.
4. umm maybe we have different types? mine are like 14 wears i think, i dont use them every day only when i go out at night or to uni or something social like that. You take them out when you get home and want to go to bed. Once they are in you dont notice them and you dont take them out until you want to leave them out.