Getting here a tad late- apologies.
I trust you will check in on the Hal Kendall stuff. It's somewhat difficult to say everything because it takes a little knowledge to understand what questions to ask. sidecar.com is a bit like this site, however, as there are folks from all over the world there.
Don't think it's been mentioned; the weight of the SC should be +/- a third of the weight of the bike with rider. Bags of cement work well, also (unless getting caught in the rain) for ballast. If the sidecar will be on the right as it is in America (don't now where you are), then right-handers are the main turns to watch for and belive me-they can sneak up and bite you on the ass real fast. It's not just on-coming cars to watch for, it's stationery light poles, walls, parked cars, whatever. Get a good overview of the free books from the site.
If properly set up, you shouldn't have to work out. You just learn to deal with the push/pull of starting and stopping. After a while, you don't even think about it.
Springs, tires, steering bearings, spokes, wheel bearngs, etc may need to be upgraded. You will probably get a new sensation known as low speed wobble. Happens around 25mph. A little is normal, especially at times of hitting small bumps and things. (this is why some people like to use a steering dampener) It should even out as you accelerate. If it continues or gets worse, just bear with it until you've come to a stop. Sometimes you can accelerrate and make a sharp turn into the car (left) to even it out, but that will take some practice and if something is really not right- it may not work anyway. Steerng bearings need to be maybe a half turn tighter than you would have set them for solo riding. And greas them, too. You can get away with street tires for a while, but they will wer relly fast and the front tire gets way more stress than solo riding. Especially in left turns, you can really feel the front tire trying to dig in- block tires give you better grip. You can guage you toe-in partly by how the rig feeels and partly by how fast the SC tire wears. If it looks pretty abraided laterally after a couple hundred miles- again, something is not right. Especially on right turns, if the bike really sags to the left and/or feels like it might roll over (like an old American car ina turn), the springs probably need to be stronger.
Veteran hackers seem to be extra solicitous to newbies. Maybe I just got carried away, but the oldtimes have seen how bad things can get with those cute sidecar thingies. We get protective.