Second, I want to know (in simple terms) what these problems mean for me if my SR20 is due to arrive in about five months. Will they have this all worked out by then?
You have nothing to worry about. There has never been an airplane manufactured without some problems in the “real world” that have to be resolved. This is an ongoing process that favors people buying later rather than people buying earlier. Earlier purchasers are those who will uncover the problems the factory never encountered. The factory will then fix those problems. The current difficulties with engines, vacuum pumps and alternators are not unusual in the early serial number airplanes, nor do they yet have a known cause. Once the cause is identified, it will be taken care of – Cirrus is a top notch organization as far as I can tell and they plan to be around for a long time. Read and learn all you can, and ask all the questions you want, but there’s no point worrying about it.
Is there any chance of switching to the Lycoming engine? Why was the Continental chosen in the first place?
With an experimental homebuilt, you can do what you want. With a certified airplane, however, you are constrained to what has been certified. In the Cirrus, the Continental is the engine of choice regardless of what you want.
As to why the C over the L, I haven’t a clue. You can bet, however, that many things were considered, including price. If both manufacturers had engines that would fit the requirments of the SR20, price may well have been a determining factor. Since you’re new to this business (I’m not), you might as well know that both of the engine manufacturers have their proponents and both have their detractors. Both companies have their ongoing technical and maintenance problems. The new SR22 has a Continental in it, so you can probably assume that this will be the engine manufacturer of choice for some time to come.