I have had quite a few outcalls to my home over the years since my ex moved out. Guess it's a little safer for me as I'm semi-rural, my nearest neighbour is 200 yds away and out of sight, and they have to drive from the nearest city, which probably weeds out ones that might hope to run off down the road.
And I've always gone along with them on the cash - some have asked for money up front, but I'd say most have left it to the end, and sometimes it's been me who's brought it up as they get ready to leave.
Most are pretty professional about leaving when time is up, but sometimes there have been over-stayers. Twice I've had them leave before the agreed time, having already been paid, but when they're like that there's not a lot to be gained by hassling them - been more than compensated by the number that have stayed longer.
One thing to watch out for is whether their clock starts when they walk in the door, or when you head for the bedroom. Got stung by this early on - the first one I saw it was only bedroom time that counted, so when the next one chatted for 1/2 hr over a cup of tea, I wasn't bothered - until she wanted to leave 1/2 hr later. Ever since, if there's any hanging around, I check the Ts & Cs :-)