I use the Volvo special tool (V5034) to hold the camshaft's sprocket gear and then tighten up on the 19mm? bolt with either a wrench or socket wrench until it is seated tight. Then I have a self sensing torque ratchet wrench from sears that I finish the job with by torquing the bolt to its proper specification. If you don't have the speciality tool you can remove the valve cover and hold the cam shaft with either a cushioned vise grip plyer or one of those large pipe wrench type plyer but both of their teeth must be cushioned with a rage to prevent damage to the cam shaft rod. The Volvo tool is # V5034 and can be obtained from Baum Tools Unlimited, Inc. (and other suppliers as well) 1-800-848-6657 or 1-941-927-1414 or www.baumtools.com. They're main location is in Sarasota Florida, but they also have outlets in San Francisco and Los Angeles California. The tool aint cheap (over $100) and then you have to insert a bolt into the threaded whole on it in order to get it to work. The bolt fits into the camshaft (or internmediate) sprocket and you apply counter pressure through a 1/2 breaker bar attached to the tool while loosening or tightening with a socket or open end 19 mm? wrench being moved counter opposite to the tools direction. If you have a sprocket holding tool from another foreign (German) automobile you might want to try it on the Volvo's sprocket to see if it holds the sprocket and save having to buy an another specialty tool. Or if you very handy in metal working you can probably fashion the tool yourself from a heavy piece of steel cut to fit in the sprocket's inside diameter and then drill and tap a bolt hole and weld on a 1/2 to 3/8 socket reduction accessory into another whole opposite from the bolt hole. Thread in the bolt and pop on the breaker bar and you're ready to go.
Sorry can't help with your other concerns as this was my first timing belt replacement and I'm still not sure I got it right? But I suspect you're going to have to disassemble the tensioner, check the parts, gently lube them, and reassemble them on the car. I put in a new tensioner roller on mine just to be sure.