Greetings fellow players
Rapid fire answers:
I never use the chat here. Most users don't.
How long they last is a thing of some contention, there's a high attrition rate but generally if it doesn't die in the first 2 or 3 months they can go for a while, and there's some on site that are years old.
It's definitely way closer to PBEM than playing it live. There's some games that can go pretty fast on site, but most don't, but then again I look for things that match my personal pace, I have a highly variable work schedule so some days I can check several times and some days I can check once or twice if I'm lucky. I try to key all my games to the slowest pace so I can always keep up.
The catch will be finding games with the right pace. There are plenty on site that only update 1/day or 2-3 times per week. I don't know how good you are at typing on your Ipad or if you have a plug in keyboard for it, but you might want to avoid the writing intensive games some people do.
There's all kinds though, I'm in some that update every day or even twice a day sometimes, and I'm in some that only update 1/week. It's all about the participants just keeping a slow and steady pace that's sustainable for them even when life gets busy.