mama - (I really want to write '..just killed a maaan' there)
OWW has it spot on here - no more than a couple of weeks if possible before meeting. If he hasn't at least mentioned meeting up before then, he's unlikely to. It's rare, I think, that a third week of chatting online makes you 50% more likely to 'click' - that really has little to do with conversation and more to do with chemistry.
Fail fast, fail cheap.
Do Not mention 'fun' or 'casual' - that's always going to be taken as you're looking for a fuckbuddy.
You could say 'Not looking for someone to live with' or 'Not looking for a husband' or something, followed by 'just someone interesting, funny, attractive and nice to spend time with' - that might get the message across.
Joy - sounds grim. It's really not fair if he says the L word first, you respond and it puts him off. What a dick.
Although it could be that saying that was a mental watershed of some sort and you suddenly felt more comfortable telling him about future plans, things like that, which scared him off? Sounds strange, I know, but saying it can mean something huge to some men, and less to others - it might be that he said it because it's just a word to him, and then seeing your response to it, it all became 'real' and too much responsibility. Dunno, to be honest.
Some people throw themselves back in - OWW did, I seem to remember - others take a break for a while. Maybe keep doing it but get more selective with who you meet for a while?