Well, AC - you're probably going to get me in trouble with the PC Police ...
1) Yes - food cooked in a PC is steamed. You might want to read this site:
How Does A Pressure Cooker Work? A PC will cook food faster. And, it can be flavorful - just like a pot roast cooked on the stovetop where the braising liquid can add to the flavor - the liquid used in the PC can add flavor. And, if you sear the roast well before cooking - you get a little more flavor from the Maillard (browning) reactions regardless of PC or pot on the stovetop.
2) You can do the same thing in a microwave - probably in less time, with the same results. Doesn't really take a lot longer in a sauce-pan with a steamer basket ... depending on the amount you are trying to cook at one time.
3) IMHO - flavor takes time to develop ... ever notice how a really good pot of chili today taste really great tomorrow? Same with a pot of stew, or tomato sauce?
4) Canner vs Cooker: Pressure Cookers are designed to heat up and cool down quickly - Pressure Canners are designed to heat up slower and cool down slower to prevent the liquid in the jars from venting out from under the lids because the pot cooled quicker than the liquid in the jars - plus they are larger to accommodate several jars. In short - you can pressure cook in a pressure canner but you can't pressure can in a pressure cooker. And, yes - the larger the pot - the longer it takes to come up to pressure/temp. If you want a multi tasker - get a pressure canner (may also be called a pressure canner/cooker).
I had my mom's PC - and it just didn't give me the same falvor results that slow cooking did. I lost it in a divorce about 25 years ago - I never replaced it.
Of course - this brings up another question: if fast food is bad for you - how do you justify the use of a PC?
(I'm now going to run off and find some cover ....)