kassadin strategies? any kass mains out there?

everytime I get mid lane, I play kassadin. I think he's a very fun champ. anyways things I struggle with.

I also struggle with just about every match up, seems like kassadin doesn't do any dmg pre-6. even after lvl 6, I feel kassadin doesn't really start dealing dmg til about lvl 10.

what do I do when the enemy jgler is camping non stop? I can't push up because they'll just walk up and get gank. keep in mind my level group is not the smartest, so my jgler just doesn't counter gank or counter jungle. let's just assume 1v5 for the sake for arguing.

also when the jgler just pushes mid with the the mid laner and its basically a 2v1 what do I do?

whenever I am doing fairly well, enemy jgler just camps river bush. I just don't know how to counter that. I feel like I get stuck and have to be forced to farm under tower. sometimes they even freeze lane cuasing me to lose a lot of cs. any ideas?

if u guys can give me any strategies, much appreciated. thank u guys