If I prepare yeast bread dough, freeze it after the 1st rising and shaping, then thaw it and let it rise again before baking, can I then freeze the cooked bread for later use? Or will it have less flavour?
Freezing does not adversely affect the flavor of bread. If anything there might be slightly more flavor from the bit of extra fermentation.
If your bread proofs sufficiently then the fact that the dough was previously frozen is irrelevant. The freezing of the dough before it is baked and freezing the bread afterwards are unrelated.
I have found that when I freeze bread the texture seems slightly more crumbly afterwards but I'm baking whole wheat bread that tends to get that way anyway.
Strictly anecdotal, that is my experience, not any studies or authoritative sources to back it up, but, the fact that you are using frozen dough should have no effect on if you freeze the finished baked bread. Freezing and thawing the dough repeatedly might cause a rising failure because too much of the yeast may be killed. A single freeze works usually because there is plenty of yeast to lose a few and still get good results. I find the frozen dough takes longer to rise, but has longer because you had to thaw it. But once it has risen, and been baked, the bread is what it is and has no memory of being frozen. The yeast is no longer alive and the flavor is set.
On lose or change, it should behave to freezing just as any other loaf would. I personally find the frozen loafs come out a bit more dry and spoil faster. They also can pick up some freezer flavor. But your bread from previously frozen dough should not have more or less tendency to this than any other loaf, it should behave the same.